Organometallic compound, organic light-emitting device including the same, and diagnostic composition including the organometallic compound

ABSTRACT

An organometallic compound represented by Formula 1A: 
     
       
         
         
             
             
         
       
         
         
           
             wherein, in Formula 1A, groups and variables are the same as described in the specification.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application to U.S. application Ser. No.17/128,400 filed on Dec. 21, 2020, a continuation application whichclaims priority to U.S. application Ser. No. 15/641,299, filed on Jul.4, 2017, which claims priority to Korean Patent Application No.10-2016-0085069, filed on Jul. 5, 2016, in the Korean IntellectualProperty Office, and all the benefits accruing therefrom under 35 U.S.C.§ 119, the contents of which are incorporated herein in their entiretyby reference.

BACKGROUND 1. Field

One or more embodiments relate to an organometallic compound, an organiclight-emitting device including the organometallic compound, and adiagnostic composition including the organometallic compound.

2. Description of the Related Art

Organic light-emitting devices (OLEDs) are self-emission devices, whichhave better characteristics including wide viewing angles, high contrastratios, short response times, and excellent brightness, driving voltage,and response speed, and produce full-color images.

In an example, an organic light-emitting device includes an anode, acathode, and an organic layer disposed between the anode and thecathode, wherein the organic layer includes an emission layer. A holetransport region may be disposed between the anode and the emissionlayer, and an electron transport region may be disposed between theemission layer and the cathode. Holes provided from the anode may movetoward the emission layer through the hole transport region, andelectrons provided from the cathode may move toward the emission layerthrough the electron transport region. The holes and the electronsrecombine in the emission layer to produce excitons. These excitonstransit from an excited state to a ground state, thereby generatinglight.

Meanwhile, luminescent compounds may be used to monitor, sense, ordetect a variety of biological materials including cells and proteins.An example of the luminescent compounds includes a phosphorescentluminescent compound.

Various types of organic light emitting devices are known. However,there still remains a need in OLEDs having low driving voltage, highefficiency, high brightness, and long lifespan.

SUMMARY

One or more embodiments include a novel organometallic compound, anorganic light-emitting device including the organometallic compound, anda diagnostic composition including the organometallic compound.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

According to one or more embodiments, an organometallic compound isrepresented by Formula 1A:

In Formula 1A,

M may be beryllium (Be), magnesium (Mg), aluminum (Al), calcium (Ca),titanium (Ti), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn),gallium (Ga), germanium (Ge), zirconium (Zr), ruthenium (Ru), rhodium(Rh), palladium (Pd), silver (Ag), rhenium (Re), platinum (Pt), or gold(Au),

X₁ may be O or S, a bond between X₁ and M may be a covalent bond,

X₂ and X₃ may each independently be C or N,

X₄ may be N,

one bond selected from a bond between X₂ and M, a bond between X₃ and M,and a bond between X₄ and M may be a covalent bond, and the othersthereof may each be a coordinate bond,

Y₁ and Y₃ to Y₅ may each independently be C or N,

a bond between X₂ and Y₃, a bond between X₂ and Y₄, a bond between Y₄and Y₅, a bond between Y₅ and X₅₁, a bond between X₅₁ and Y₃ may each bea chemical bond,

CY₁ to CY₅ may each independently be selected from a C₅-C₃₀ carbocyclicgroup and a C₁-C₃₀ heterocyclic group, wherein CY₄ is not abenzimidazole group,

a cyclometallated ring formed by CY₅, CY₂, CY₃, and M may be a6-membered ring,

X₅₁ may be selected from O, S, N-[(L₇)_(b7)−(R₇)_(c7)], C(R₇)(R₈),Si(R₇)(R₈), Ge(R₇)(R₈), C(═O), N, C(R₇), Si(R₇), and Ge(R₇),

R₇ and R₈ may be optionally linked via a first linking group to form asubstituted or unsubstituted C₅-C₃₀ carbocyclic group or a substitutedor unsubstituted C₁-C₃₀ heterocyclic group,

L₁ to L₄ and L₇ may each independently be selected from a substituted orunsubstituted C₅-C₃₀ carbocyclic group and a substituted orunsubstituted C₁-C₃₀ heterocyclic group,

b1 to b4 and b7 may each independently be an integer from 0 to 5,

R₁ to R₄, R₇, and R₈ may each independently be selected from hydrogen,deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano group, anitro group, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a substituted orunsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, asubstituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted orunsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstitutedC₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ arylgroup, a substituted or unsubstituted C₆-C₆₀ aryloxy group, asubstituted or unsubstituted C₆-C₆₀ arylthio group, a substituted orunsubstituted C₇-C₆₀ arylalkyl group, a substituted or unsubstitutedC₁-C₆₀ heteroaryl group, a substituted or unsubstituted C₂-C₆₀heteroaryloxy group, a substituted or unsubstituted C₂-C₆₀heteroarylthio group, a substituted or unsubstituted C₃-C₆₀heteroarylalkyl group, a substituted or unsubstituted monovalentnon-aromatic condensed polycyclic group, a substituted or unsubstitutedmonovalent non-aromatic condensed heteropolycyclic group, —N(Q₁)(Q₂),—Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉),

c1 to c4 may each independently be an integer from 1 to 5,

a1 to a4 may each independently be 0, 1, 2, 3, 4, or 5,

two of a plurality of neighboring groups R₁ may optionally be linked toform a substituted or unsubstituted C₅-C₃₀ carbocyclic group or asubstituted or unsubstituted C₁-C₃₀ heterocyclic group,

two of a plurality of neighboring groups R₂ may optionally be linked toform a substituted or unsubstituted C₅-C₃₀ carbocyclic group or asubstituted or unsubstituted C₁-C₃₀ heterocyclic group,

two of a plurality of neighboring groups R₃ may optionally be linked toform a substituted or unsubstituted C₅-C₃₀ carbocyclic group or asubstituted or unsubstituted C₁-C₃₀ heterocyclic group,

two of a plurality of neighboring groups R₄ may optionally be linked toform a substituted or unsubstituted C₅-C₃₀ carbocyclic group or asubstituted or unsubstituted C₁-C₃₀ heterocyclic group,

two or more neighboring groups selected from R₁ to R₄ may optionally belinked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic groupor a substituted or unsubstituted C₁-C₃₀ heterocyclic group,

a1 to a4 may each independently be 1, 2, 3, 4, or 5, and at least oneselected from R₁ to R₄ may be selected from a substituted orunsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstitutedC₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ arylgroup, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, asubstituted or unsubstituted monovalent non-aromatic condensedpolycyclic group, and a substituted or unsubstituted monovalentnon-aromatic condensed heteropolycyclic group, in the cases where i) Mis Pt, ii) X₁ is O, iii) X₂ and X₄ are each N, X₃ is C, a bond betweenX₂ and M and a bond between X₄ and M are each a coordinate bond, and abond between X₃ and M is a covalent bond, iv) Y₁ to Y₅ are each C, v) abond between Y₅ and X₅₁ and a bond between Y₃ and X₅₁ are each a singlebond, vi) CY₁, CY₂, and CY₃ are each a benzene group, and CY₄ is apyridine group, vii) X₅₁ is O, S, or N-[(L₇)_(b7)-(R₇)_(c7)], and viii)b7 is 0, c7 is 1, and R₇ is a substituted or unsubstituted C₁-C₆₀ alkylgroup,

at least one substituent of the substituted C₅-C₃₀ carbocyclic group,the substituted C₁-C₃₀ heterocyclic group, the substituted C₁-C₆₀ alkylgroup, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substitutedC₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group,the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, thesubstituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group,the substituted C₇-C₆₀ arylalkyl group, the substituted C₁-C₆₀heteroaryl group, the substituted C₂-C₆₀ heteroaryloxy group, thesubstituted C₂-C₆₀ heteroarylthio group, the substituted C₃-C₆₀heteroarylalkyl group, the substituted monovalent non-aromatic condensedpolycyclic group, and the substituted monovalent non-aromatic condensedheteropolycyclic group may be selected from:

deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, aC₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group;

a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group,and a C₁-C₆₀ alkoxy group, each substituted with at least one selectedfrom deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H,—CFH₂, a hydroxyl group, a cyano group, a nitro group, an amidino group,a hydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroarylgroup, a C₂-C₆₀ heteroaryloxy group, a C₂-C₆₀ heteroarylthio group, aC₃-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensedpolycyclic group, a monovalent non-aromatic condensed heteropolycyclicgroup, —N(Q₁₁)(Q₁₂), —S(Q₁₃)(Q₁₄)(Q₁₅), —B(Q₁₆)(Q₁₇), and—P(═O)(Q₁₈)(Q₁₉);

a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ heteroaryloxygroup, a C₂-C₆₀ heteroarylthio group, a C₃-C₆₀ heteroarylalkyl group, amonovalent non-aromatic condensed polycyclic group, and a monovalentnon-aromatic condensed heteropolycyclic group;

a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ heteroaryloxygroup, a C₂-C₆₀ heteroarylthio group, a C₃-C₆₀ heteroarylalkyl group, amonovalent non-aromatic condensed polycyclic group, and a monovalentnon-aromatic condensed heteropolycyclic group, each substituted with atleast one selected from deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂,—CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, C₁-C₆₀ alkyl group, a C₂-C₆₀alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenylgroup, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, aC₁-C₆₀ heteroaryl group, a C₂-C₆₀ heteroaryloxy group, a C₂-C₆₀heteroarylthio group, a C₃-C₆₀ heteroarylalkyl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅),—B(Q₂₆)(Q₂₇), and —P(═O)(Q₂₈)(Q₂₉); and

—N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and —P(═O)(Q₃₈)(Q₃₉),and

Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ may each independentlybe selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxylgroup, a cyano group, a nitro group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₆₀ alkyl group, a C₁-C₆₀ alkyl group substituted with atleast one selected from deuterium, a C₁-C₆₀ alkyl group, and a C₆-C₆₀aryl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkylgroup, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, aC₆-C₆₀ aryl group, a C₃-C₆₀ aryl group substituted with at least oneselected from deuterium, a C₁-C₆₀ alkyl group, and a C₆-C₆₀ aryl group,a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkylgroup, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ heteroaryloxy group, a C₂-C₆₀heteroarylthio group, a C₃-C₆₀ heteroarylalkyl group, a monovalentnon-aromatic condensed polycyclic group, and a monovalent non-aromaticcondensed heteropolycyclic group.

According to one or more embodiments, an organic light-emitting deviceincludes:

a first electrode;

a second electrode; and

an organic layer disposed between the first electrode and the secondelectrode,

wherein the organic layer includes an emission layer and at least oneorganometallic compound.

The organometallic compound may act as a dopant in the organic layer.

According to one or more embodiments, a diagnostic composition includesat least one of the organometallic compound represented by Formula 1A.

BRIEF DESCRIPTION OF THE DRAWING

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the FIGURE which is a schematic view of an organiclight-emitting device according to an embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the presentembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects of the present description. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items. Expressions such as “at least one of,” whenpreceding a list of elements, modify the entire list of elements and donot modify the individual elements of the list.

It will be understood that when an element is referred to as being “on”another element, it can be directly in contact with the other element orintervening elements may be present therebetween. In contrast, when anelement is referred to as being “directly on” another element, there areno intervening elements present.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers, and/or sections, these elements, components, regions, layers,and/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer, orsection from another element, component, region, layer, or section.Thus, a first element, component, region, layer, or section discussedbelow could be termed a second element, component, region, layer, orsection without departing from the teachings of the present embodiments.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise.

The term “or” means “and/or.” It will be further understood that theterms “comprises” and/or “comprising,” or “includes” and/or “including”when used in this specification, specify the presence of statedfeatures, regions, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, regions, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this general inventive conceptbelongs. It will be further understood that terms, such as those definedin commonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand the present disclosure, and will not be interpreted in an idealizedor overly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

In an embodiment, an organometallic compound is provided.

An organometallic compound according to an embodiment may be representedby Formula 1A:

In Formula 1A, M may be beryllium (Be), magnesium (Mg), aluminum (Al),calcium (Ca), titanium (Ti), manganese (Mn), cobalt (Co), copper (Cu),zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), ruthenium (Ru),rhodium (Rh), palladium (Pd), silver (Ag), rhenium (Re), platinum (Pt),or gold (Au).

For example, M in Formula 1A may be platinum (Pt), but embodiments ofthe present disclosure are not limited thereto.

The organometallic compound represented by Formula 1A may be a neutralcompound which does not consist of an ion pair of an anion and a cation.

In Formula 1A, X₁ may be O or S, and a bond between X₁ and M may be acovalent bond.

For example, in Formula 1A, X₁ may be O, but embodiments of the presentdisclosure are not limited thereto.

In Formula 1A, X₂ and X₃ may each independently be C or N, and X₄ may beN.

In an embodiment, in Formula 1A, X₃ may be C, and X₂ and X₄ may each beN.

In Formula 1A, one bond selected from a bond between X₂ and M, a bondbetween X₃ and M, and a bond between X₄ and M may be a covalent bond,and the others thereof may each be a coordinate bond.

In an embodiment, a bond between X₂ and M and a bond between X₄ and Mmay each be a coordinate bond, and a bond between X₃ and M may be acovalent bond.

For example, in Formula 1A,

i) X₂ and X₄ may each be N, X₃ may be C, a bond between X₂ and M and abond between X₄ and M may each be a coordinate bond, and a bond betweenX₃ and M may be a covalent bond; or

ii) X₃ and X₄ may each be N, X₂ may be C, a bond between X₃ and M and abond between X₄ and M may each be a coordinate bond, and a bond betweenX₂ and M may be a covalent bond.

In Formula 1A, Y₁ and Y₃ to Y₅ may each independently be C or N.

For example, in Formula 1A, Y₁ and Y₃ may each be C, but embodiments ofthe present disclosure are not limited thereto.

In Formula 1A, a bond between X₂ and Y₃, a bond between X₂ and Y₄, bondbetween Y₄ and Y₅, a bond between Y₅ and X₅₁, and a bond between X₅₁ andY₃ may each be a chemical bond (for example, a single bond, a doublebond, a covalent bond or the like).

In Formula 1A, CY₁ to CY₅ may each independently be selected from aC₅-C₃₀ carbocyclic group and a C₁-C₃₀ heterocyclic group. Here, CY₄ isnot a benzimidazole group.

For example, in Formula 1A, CY₁ to CY₄ may each independently beselected from a) a 6-membered ring, b) a condensed ring having two ormore 6-membered rings that are condensed to each other, and c) acondensed ring having two or more 6-membered rings and one 5-memberedring that are condensed to each other, wherein the 6-membered ring maybe selected from a cyclohexane group, a cyclohexene group, an adamantanegroup, a norbornane group, a norbornene group, a benzene group, apyridine group, a pyrimidine group, a pyrazine group, a pyridazinegroup, and a triazine group, and the 5-membered ring may be selectedfrom a cyclopentane group, a cyclopentene group, a cyclopentadienegroup, a furan group, a thiophene group, a silole group, a pyrrolegroup, a pyrazole group, an imidazole group, a triazole group, anoxazole group, an isoxazole group, a thiazole group, an isothiazolegroup, an oxadiazole group, and a thiadiazole group.

In an embodiment, CY₁ to CY₄ may each independently be selected from abenzene group, a naphthalene group, an anthracene group, a phenanthrenegroup, a triphenylene group, a pyrene group, a chrysene group, acyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a furangroup, a thiophene group, silole group, an indene group, a fluorenegroup, an indole group, a carbazole group, a benzofuran group, adibenzofuran group, a benzothiophene group, a dibenzothiophene group, abenzosilole group, a dibenzosilole group, an azafluorene group, anazacarbazole group, an azadibenzofuran group, an azadibenzothiophenegroup, azadibenzosilole group, a pyridine group, a pyrimidine group, apyrazine group, a pyridazine group, a triazine group, a quinoline group,an isoquinoline group, a quinoxaline group, a quinazoline group,phenanthroline group, a cinnoline group, a phthalazine group, a pyrrolegroup, a pyrazole group, an imidazole group, a triazole group, anoxazole group, an iso-oxazole group, a thiazole group, an isothiazolegroup, an oxadiazole group, a thiadiazole group, a benzopyrazole group,a benzimidazole group, a benzoxazole group, a benzothiazole group, abenzooxadiazole group, a benzothiadiazole group, a5,6,7,8-tetrahydroisoquinoline group, a 5,6,7,8-tetrahydroquinolinegroup, a 5,6,7,8-tetrahydrophthalazine group, and a5,6,7,8-tetrahydrocinnoline group.

In one or more embodiments, CY₁ to CY₄ may each independently beselected from a benzene group, a naphthalene group, an anthracene group,a phenanthrene group, a triphenylene group, a pyrene group, a chrysenegroup, a cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, afluorene group, a carbazole group, a dibenzofuran group, adibenzothiophene group, a dibenzosilole group, an azafluorene group, anazacarbazole group, an azadibenzofuran group, an azadibenzothiophenegroup, an azadibenzosilole group, a pyridine group, a pyrimidine group,a pyrazine group, a pyridazine group, a triazine group, a quinolinegroup, an isoquinoline group, a quinoxaline group, a quinazoline group,a phenanthroline group, a cinnoline group, a phthalazine group, a5,6,7,8-tetrahydroisoquinoline group, a 5,6,7,8-tetrahydroquinolinegroup, a 5,6,7,8-tetrahydrophthalazine group, and a5,6,7,8-tetrahydrocinnoline group, but embodiments of the presentdisclosure are not limited thereto.

In Formula 1A, CY₅ may be a 5-membered ring.

In Formula 1A, a cyclometallated ring formed by CY₅, CY₂, CY₃, and M maybe a 6-membered ring.

In Formula 1A, X₅₁ may be selected from O, S, N-[(L₇)_(b7)-(R₇)_(c7)],C(R₇)(R₈), Si(R₇)(R₈), Ge(R₇)(R₈), C(═O), N, C(R₇), Si(R₇), and Ge(R₇),R₇ and R₈ may be optionally linked via a first linking group to form asubstituted or unsubstituted C₅-C₃₀ carbocyclic group or a substitutedor unsubstituted C₁-C₃₀ heterocyclic group (for example, aC₅-C₆-membered to 7-membered cyclic group, or a C₅-C₆-membered to7-membered cyclic group substituted with at least one of deuterium, acyano group, —F, a C₁-C₁₀ alkyl group, and a C₆-C₁₄ aryl group). Here,L₇, b7, R₇, c7, and R₈ are each independently the same as describedbelow.

The first linking group may be selected from a single bond, *—O—*′,*—S—*′, *—C(R₅)(R₆)—*′, *—C(R₅)═*′, *═C(R₅)—*′, *—C(R₅)═C(R₆)—*′,*—C(═O)—*′, *—C(═S)—*′, *—C≡C—*′, *—N(R₅)—*′, *—Si(R₅)(R₆)—*′, and*—P(R₅)(R₆)—*′, R₅ and R₆ are each independently the same as describedin connection with R₁, and * and *′ each indicate a binding site to aneighboring atom.

In Formula 1A, L₁ to L₄ and L₇ may each independently be selected from asubstituted or unsubstituted C₅-C₃₀ carbocyclic group and a substitutedor unsubstituted C₁-C₃₀ heterocyclic group.

For example, in Formula 1A, L₁ to L₄ and L₇ may each independently beselected from:

a benzene group, a naphthalene group, an anthracene group, aphenanthrene group, a triphenylene group, a pyrene group, a chrysenegroup, a cyclopentadiene group, a furan group, a thiophene group, silolegroup, an indene group, a fluorene group, an indole group, a carbazolegroup, a benzofuran group, a dibenzofuran group, a benzothiophene group,a dibenzothiophene group, a benzosilole group, a dibenzosilole group, anazafluorene group, an azacarbazole group, an azadibenzofuran group, anazadibenzothiophene group, azadibenzosilole group, a pyridine group, apyrimidine group, a pyrazine group, a pyridazine group, a triazinegroup, a quinoline group, an isoquinoline group, a quinoxaline group, aquinazoline group, phenanthroline group, a pyrrole group, a pyrazolegroup, an imidazole group, a triazole group, an oxazole group, aniso-oxazole group, a thiazole group, an isothiazole group, an oxadiazolegroup, a thiadiazole group, a benzopyrazole group, a benzimidazolegroup, a benzoxazole group, a benzothiazole group, a benzooxadiazolegroup, and a benzothiadiazole group; and

a benzene group, a naphthalene group, an anthracene group, aphenanthrene group, a triphenylene group, a pyrene group, a chrysenegroup, a cyclopentadiene group, a furan group, a thiophene group, silolegroup, an indene group, a fluorene group, an indole group, a carbazolegroup, a benzofuran group, a dibenzofuran group, a benzothiophene group,a dibenzothiophene group, a benzosilole group, a dibenzosilole group, anazafluorene group, an azacarbazole group, an azadibenzofuran group, anazadibenzothiophene group, azadibenzosilole group, a pyridine group, apyrimidine group, a pyrazine group, a pyridazine group, a triazinegroup, a quinoline group, an isoquinoline group, a quinoxaline group, aquinazoline group, phenanthroline group, a pyrrole group, a pyrazolegroup, an imidazole group, a triazole group, an oxazole group, aniso-oxazole group, a thiazole group, an isothiazole group, an oxadiazolegroup, a thiadiazole group, a benzopyrazole group, a benzimidazolegroup, a benzoxazole group, a benzothiazole group, a benzooxadiazolegroup, and a benzothiadiazole group, each substituted with at least oneselected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, anaphthyl group, a pyridinyl group, a pyrimidinyl group, a triazinylgroup, a fluorenyl group, a dimethylfluorenyl group, a diphenylfluorenylgroup, a carbazolyl group, a phenylcarbazolyl group, a dibenzofuranylgroup, a dibenzothiophenyl group, a dibenzosilolyl group, adimethyldibenzosilolyl group, a diphenyldibenzosilolyl group,—N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and —P(═O)(Q₃₈)(Q₃₉),

Q₃₁ to Q₃₉ may each independently be selected from:

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an iso-propyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and

an n-propyl group, an iso-propyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom deuterium, a C₁-C₁₀ alkyl group, and a phenyl group,

but embodiments of the present disclosure are not limited thereto.

In an embodiment, in Formula 1A, L₁ to L₄ and L₇ may each independentlybe selected from:

a benzene group, a pyridine group, and a pyrimidine group; and

a benzene group, a pyridine group, and a pyrimidine group, eachsubstituted with at least one selected from deuterium, —F, —Cl, —Br, —I,a hydroxyl group, a cyano group, a nitro group, an amino group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀alkoxy group, a phenyl group, a pyridinyl group, and a pyrimidinylgroup, —N(Q₃₁)(Q₃₂), —S(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and—P(═O)(Q₃₈)(Q₃₉) (wherein Q₃₁ to Q₃₉ are each independently the same asdescribed herein),

but embodiments of the present disclosure are not limited thereto.

In Formula 1A, b1 to b4 and b7 respectively indicate the number of L₁ toL₄ and L₇, and may each independently be an integer from 0 to 5. When b1is 0, *-(L₁)_(b1)-*′ may be a single bond. When b1 is two or more, twoor more groups L₁ may be identical to or different from each other. b2to b4 and b7 are each independently the same as described in connectionwith b1.

In an embodiment, in Formula 1A, b1 to b4 and b7 may be eachindependently 0 or 1, but embodiments of the present disclosure are notlimited thereto.

In Formula 1A, R₁ to R₄, R₇, and R₈ may each independently be selectedfrom hydrogen, deuterium, —F, —C, —Br, —I, —SF₅, a hydroxyl group, acyano group, a nitro group, an amidino group, a hydrazine group, ahydrazone group, a carboxylic acid group or a salt thereof, a sulfonicacid group or a salt thereof, a phosphoric acid group or a salt thereof,a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted orunsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstitutedC₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxygroup, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, asubstituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted orunsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted orunsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, asubstituted or unsubstituted C₇-C₆₀ arylalkyl group, a substituted orunsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstitutedC₂-C₆₀ heteroaryloxy group, a substituted or unsubstituted C₂-C₆₀heteroarylthio group, a substituted or unsubstituted C₃-C₆₀heteroarylalkyl group, a substituted or unsubstituted monovalentnon-aromatic condensed polycyclic group, a substituted or unsubstitutedmonovalent non-aromatic condensed heteropolycyclic group, —N(Q₁)(Q₂),—Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉).

For example, R₁ to R₄, R₇, and R₈ may each independently be selectedfrom:

hydrogen, deuterium, —F, —C, —Br, —I, a hydroxyl group, a cyano group, anitro group, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, —SF₅, a C₁-C₂₀ alkylgroup, and a C₁-C₂₀ alkoxy group;

a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted with atleast one selected from deuterium, —F, —C, —Br, —I, —CD₃, —CD₂H, —CDH₂,—CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl (adamantyl) group, a norbornanyl (norbornyl)group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,a cycloheptenyl group, a phenyl group, a naphthyl group, a pyridinylgroup, and a pyrimidinyl group;

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, and animidazopyrimidinyl group;

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, and animidazopyrimidinyl group, each substituted with at least one selectedfrom deuterium, —F, —C, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂,a hydroxyl group, a cyano group, a nitro group, an amino group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, animidazopyrimidinyl group and —Si(Q₃₃)(Q₃₄)(Q₃₅); and

—N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉), and

Q₁ to Q₉ and Q₃₃ to Q₃₅ are each independently the same as described inconnection with Q₃₁.

In an embodiment, R₁ to R₄, R₇, and R₈ may each independently beselected from:

hydrogen, deuterium, —F, a cyano group, a nitro group, —SF₅, a methylgroup, an ethyl group, an n-propyl group, an iso-propyl group, ann-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group,an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentylgroup, an n-hexyl group, an iso-hexyl group, a sec-hexyl group, atert-hexyl group, an n-heptyl group, an iso-heptyl group, a sec-heptylgroup, a tert-heptyl group, an n-octyl group, an iso-octyl group, asec-octyl group, a tert-octyl group, an n-nonyl group, an iso-nonylgroup, a sec-nonyl group, a tert-nonyl group, an n-decyl group, aniso-decyl group, a sec-decyl group, a tert-decyl group, a methoxy group,an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl group, a norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group,a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, adibenzothiophenyl group, and a dibenzosilolyl group;

a methyl group, an ethyl group, an n-propyl group, an iso-propyl group,an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butylgroup, an n-pentyl group, an isopentyl group, a sec-pentyl group, atert-pentyl group, an n-hexyl group, an iso-hexyl group, a sec-hexylgroup, a tert-hexyl group, an n-heptyl group, an iso-heptyl group, asec-heptyl group, a tert-heptyl group, an n-octyl group, an iso-octylgroup, a sec-octyl group, a tert-octyl group, an n-nonyl group, aniso-nonyl group, a sec-nonyl group, a tert-nonyl group, an n-decylgroup, an iso-decyl group, a sec-decyl group, a tert-decyl group, amethoxy group, an ethoxy group, a propoxy group, a butoxy group, apentoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a pyridinylgroup, a pyrimidinyl group, a fluorenyl group, a carbazolyl group, adibenzofuranyl group, a dibenzothiophenyl group, and a dibenzosilolylgroup, each substituted with at least one selected from deuterium, —F,—CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano group, a nitro group, aC₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, a norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group,a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group and —Si(Q₃₃)(Q₃₄)(Q₃₅);and

—N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉), and

Q₁ to Q₉ and Q₃₃ to Q₃₅ are each independently the same as describedherein, but embodiments of the present disclosure are not limitedthereto.

In one or more embodiments, R₁ to R₄, R₇, and R₈ may each independentlybe selected from hydrogen, deuterium, —F, a cyano group, a nitro group,—SF₅, —CH₃, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, —C₂F₅, —C₂F₄H,—C₂F₃H₂, —C₂F₂H₃, —C₂FH₄, groups represented by Formulae 9-1 to 9-19,groups represented by Formulae 10-1 to 10-167, —N(Q₁)(Q₂),—Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉) (wherein Q₁ to Q₉ areeach independently the same as described herein), but embodiments of thepresent disclosure are not limited thereto:

In groups represented by Formulae 9-1 to 9-19 and Formulae 10-1 to10-167, * indicate a binding site to a neighboring group, “Ph” indicatesa phenyl group, and “TMS” indicates a trimethylsilyl group.

In Formula 1A, c1 to c4 respectively indicate the number of R₁ to R₄,and may each independently be an integer from 1 to 5. When c1 is two ormore, two or more groups R₁ may be identical to or different from eachother. c2 to c4 are each independently the same as described inconnection with c1.

In an embodiment, in Formula 1A, c1 to c4 may each independently be 1 or2, but embodiments of the present disclosure are not limited thereto.

In Formula 1A, a1 to a4 respectively indicate the number of*—[(L₁)_(b1)-(R₁)_(c1)], *—[(L₂)_(b2)-(R₂)_(c2)],*—[(L₃)_(b3)-(R₃)_(c3)], and *—[(L₄)_(b4)-(R₄)_(c4)], and may eachindependently be 0, 1, 2, 3, 4, or 5. When a1 is two or more, two ormore groups *—[(L₁)_(b1)-(R₁)_(c1)] may be identical to or differentfrom each other. When a2 is two or more, two or more groups*—[(L₂)_(b2)-(R₂)_(c2)] may be identical to or different from eachother. When a3 is two or more, two or more groups*—[(L₃)_(b3)-(R₃)_(c3)] may be identical to or different from eachother. When a4 is two or more, two or more groups*—[(L₄)_(b4)-(R₄)_(c4)] may be identical to or different from eachother. However, embodiments of the present disclosure are not limitedthereto.

For example, in Formula 1A, a1 to a4 may each independently be 1, 2, 3,4, or 5, and

i) at least one selected from R₁ to R₄ may not be hydrogen,

ii) at least one selected from R₁, R₂, and R₄ may not be hydrogen,

iii) at least one selected from R₁ to R₃ may not be hydrogen, or

iv) at least one selected from R₁ and R₂ may not be hydrogen, butembodiments of the present disclosure are not limited thereto.

In Formula 1A, i) two of a plurality of neighboring groups R₁ mayoptionally be linked to form a substituted or unsubstituted C₅-C₃₀carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclicgroup, ii) two of a plurality of neighboring groups R₂ may optionally belinked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic groupor a substituted or unsubstituted C₁-C₃₀ heterocyclic group, iii) two ofa plurality of neighboring groups R₃ may optionally be linked to form asubstituted or unsubstituted C₅-C₃₀ carbocyclic group or a substitutedor unsubstituted C₁-C₃₀ heterocyclic group, iv) two of a plurality ofneighboring groups R₄ may optionally be linked to form a substituted orunsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstitutedC₁-C₃₀ heterocyclic group, and v) two or more neighboring groupsselected from R₁ to R₄ may optionally be linked to form a substituted orunsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstitutedC₁-C₃₀ heterocyclic group.

For example, in Formula 1A, i) a substituted or unsubstituted C₅-C₃₀carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclicgroup, formed by linking two of a plurality of neighboring groups R₁,ii) a substituted or unsubstituted C₅-C₃₀ carbocyclic group or asubstituted or unsubstituted C₁-C₃₀ heterocyclic group, formed bylinking two of a plurality of neighboring groups R₂, iii) a substitutedor unsubstituted C₅-C₃₀ carbocyclic group or a substituted orunsubstituted C₁-C₃₀ heterocyclic group, formed by linking two of aplurality of neighboring groups R₃, iv) a substituted or unsubstitutedC₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀heterocyclic group, formed by linking two of a plurality of neighboringgroups R₄, and v) a substituted or unsubstituted C₅-C₃₀ carbocyclicgroup or a substituted or unsubstituted C₁-C₃₀ heterocyclic group,formed by linking two or more neighboring groups selected from R₁ to R₄may each independently be selected from:

a cyclopentadiene group, a cyclohexane group, a cycloheptane group, anadamantane group, a norbornane group, a norbornene group, abicycle-heptane group, a bicyclo-octane group, a benzene group, apyridine group, a pyrimidine group, a pyrazine group, a pyridazinegroup, a triazine group, a naphthalene group, an anthracene group, atetracene group, a phenanthrene group, a dihydronaphthalene group, aphenalene group, a benzothiophene group, a benzofuran group, an indenegroup, an indole group, a benzosilole group, an azabenzothiophene group,an azabenzofuran group, an azaindene group, an azaindole group, and anazabenzosilole group; and

a cyclopentadiene group, a cyclohexane group, a cycloheptane group, anadamantane group, a norbornane group, a norbornene group, abicycle-heptane group, a bicyclo-octane group, a benzene group, apyridine group, a pyrimidine group, a pyrazine group, a pyridazinegroup, a triazine group, a naphthalene group, an anthracene group, atetracene group, a phenanthrene group, a dihydronaphthalene group, aphenalene group, a benzothiophene group, a benzofuran group, an indenegroup, an indole group, a benzosilole group, an azabenzothiophene group,an azabenzofuran group, an azaindene group, an azaindole group, and anazabenzosilole group, each substituted with at least one R_(1a),

but embodiments of the present disclosure are not limited thereto.

R_(1a) may be the same as described in connection with R₁.

“An azabenzothiophene group, an azabenzofuran group, an azaindene group,an azaindole group, an azabenzosilole group, an azadibenzothiophenegroup, an azadibenzofuran group, an azafluorene group, an azacarbazolegroup, and an azadibenzosilole group” as used herein mean hetero-ringsthat respectively have the same backbones as “a benzothiophene group, abenzofuran group, an indene group, an indole group, a benzosilole group,a dibenzothiophene group, a dibenzofuran group, a fluorene group, acarbazole group, and a dibenzosilole group’, wherein at least one ofcarbons forming rings thereof is substituted with nitrogen.

In an embodiment, in Formula 1A,

i) a bond between Y₃ and X₅₁ and a bond between Y₅ and X₅₁ may each be asingle bond, and X₅₁ may be C(R₇)(R₈), Si(R₇)(R₈), or C(═O),

ii) a bond between Y₃ and X₅₁ and a bond between Y₅ and X₅₁ may each bea single bond, X₅₁ may be N-[(L₇)_(b7)-(R₇)_(c7)], and R₇ may beselected from a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, asubstituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted orunsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted orunsubstituted C₅-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, asubstituted or unsubstituted C₇-C₆₀ arylalkyl group, a substituted orunsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstitutedC₂-C₆₀ heteroaryloxy group, a substituted or unsubstituted C₂-C₆₀heteroarylthio group, a substituted or unsubstituted C₃-C₆₀heteroarylalkyl group, a substituted or unsubstituted monovalentnon-aromatic condensed polycyclic group, and a substituted orunsubstituted monovalent non-aromatic condensed heteropolycyclic group,or

iii) one bond selected from a bond between Y₃ and X₅₁ and a bond betweenY₅ and X₅₁ may be a single bond, and the others thereof may each be adouble bond, and X₅₁ may be N, C(R₇), or Si(R₇).

In one or more embodiments, in Formula 1A, X₅₁ may beN-[(L₇)_(b7)-(R₇)_(c7)], and R₇ may be selected from:

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, and animidazopyrimidinyl group; and

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, and animidazopyrimidinyl group, each substituted with at least one selectedfrom deuterium, —F, —C, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂,a hydroxyl group, a cyano group, a nitro group, an amino group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a benzocarbazolyl group, a dibenzosilolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, animidazopyrimidinyl group, and —Si(Q₃₃)(Q₃₄)(Q₃₅), and

Q₃₃ to Q₃₅ are each independently the same as described herein.

In one or more embodiments, in Formula 1A, X₅₁ may beN-[(L₇)_(b7)-(R₇)_(c7)], and R₇ may be selected from groups representedby Formulae 10-1 to 10-128 and groups represented by Formulae 10-131 to10-167, but embodiments of the present disclosure are not limitedthereto.

In one or more embodiments, in Formula 1A,

in cases where i) M is Pt, ii) X₁ is O, iii) X₂ and X₄ are each N, X₃ isC, a bond between X₂ and M and a bond between X₄ and M are each acoordinate bond, and a bond between X₃ and M is a covalent bond, iv) Y₁to Y₅ are each C, v) a bond between Y₅ and X₅₁ and a bond between Y₃ andX₅₁ are each a single bond, vi) CY₁, CY₂, and CY₃ are each a benzenegroup, and CY₄ is a pyridine group, vii) X₅₁ is O, S, orN-[(L₇)_(b7)-(R₇)_(c7)], and viii) b7 is 0, c7 is 1, and R₇ is asubstituted or unsubstituted C₁-C₆₀ alkyl group,

a1 to a4 may each independently be 1, 2, 3, 4, or 5, and at least oneselected from R₁ to R₄ may be selected from a substituted orunsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstitutedC₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ arylgroup, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, asubstituted or unsubstituted monovalent non-aromatic condensedpolycyclic group, and a substituted or unsubstituted monovalentnon-aromatic condensed heteropolycyclic group.

In one or more embodiments, Formula 1A, in which X₅₁ may be O, S, orN-[(L₇)_(b7)-(R₇)_(c7)], b7 may be 0, c7 may be 1, and R₇ may be asubstituted or unsubstituted C₁-C₆₀ alkyl group may be satisfied with atleast one selected from “Condition 1” to “Condition 6”:

Condition 1

M may be beryllium (Be), magnesium (Mg), aluminum (Al), calcium (Ca),titanium (Ti), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn),gallium (Ga), germanium (Ge), zirconium (Zr), ruthenium (Ru), rhodium(Rh), palladium (Pd), silver (Ag), rhenium (Re), or gold (Au);

Condition 2

X₁ may be S

Condition 3

X₃ and X₄ may each be N, X₂ may be C, a bond between X₃ and M and a bondbetween X₄ and M may each be a coordinate bond, and a bond between X₂and M may be a covalent bond;

Condition 4

at least one selected from Y₁ to Y₅ may not be C;

Condition 5

at least one selected from CY₁, CY₂, and CY₃ may not be a benzene group;and

Condition 6

CY₄ may not be a pyridine group

In one or more embodiments, the organometallic compound may berepresented by Formula 1A, wherein

M may be Pt,

X₁ may be O,

X₂ and X₄ may each be N, X₃ may be C, a bond between X₂ and M and a bondbetween X₄ and M may each be a coordinate bond, a bond between X₃ and Mmay be a covalent bond,

Y₁ to Y₅ may each be C,

a bond between Y₅ and X₅₁, a bond between Y₃ and X₅₁ may each be asingle bond,

CY₁, CY₂, and CY₃ may each be a benzene group, CY₄ may be a pyridinegroup,

X₅₁ may be O, S, or N-[(L₇)_(b7)-(R₇)_(c7)],

b7 may be 0, c7 may be 1, R₇ may be a substituted or unsubstitutedC₁-C₆₀ alkyl group,

a1 to a4 may each independently be 1, 2, 3, or 4, and

at least one selected from R₁ to R₄ may each independently be selectedfrom a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, asubstituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted orunsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted orunsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₁-C₆₀heteroaryl group, a substituted or unsubstituted monovalent non-aromaticcondensed polycyclic group, and a substituted or unsubstitutedmonovalent non-aromatic condensed heteropolycyclic group.

In one or more embodiments, the organometallic compound may berepresented by Formula 1A, wherein

M may be Pt,

X₁ may be O,

X₂ and X₄ may each be N, X₃ may be C, a bond between X₂ and M and a bondbetween X₄ and M may each be a coordinate bond, a bond between X₃ and Mmay be a covalent bond,

Y₁ to Y₅ may each be C,

a bond between Y₅ and X₅₁, a bond between Y₃ and X₅₁ may each be asingle bond,

CY₁, CY₂, and CY₃ may each be a benzene group, CY₄ may be a pyridinegroup,

X₅₁ may be O, S, or N-[(L₇)_(b7)-(R₇)_(c7)],

b7 may be 0, c7 may be 1,

R₇ may be selected from:

a C₁-C₃₀ alkyl group; and

a C₁-C₃₀ alkyl group substituted with at least one selected fromdeuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl group, a norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinylgroup,

a1 to a4 may each independently be 1, 2, 3, or 4, and

at least one selected from R₁ to R₄ may each independently be selectedfrom:

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a benzocarbazolyl group, a dibenzosilolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, and animidazopyrimidinyl group; and

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, and animidazopyrimidinyl group, each substituted with at least one selectedfrom deuterium, —F, —C, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂,a hydroxyl group, a cyano group, a nitro group, an amino group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, animidazopyrimidinyl group, and —Si(Q₃₃)(Q₃₄)(Q₃₅) (wherein Q₃₃ to Q₃₅ areeach independently the same as described herein),

but embodiments of the present disclosure are not limited thereto.

In one or more embodiments, in Formula 1A,

X₅₁ may be O, S, or N-[(L₇)_(b7)-(R₇)_(c7)], b7 may be 0, c7 may be 1,

R₇ may be selected from:

a C₁-C₃₀ alkyl group, and

a C₁-C₃₀ alkyl group substituted with at least one selected fromdeuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl group, a norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinylgroup,

a1 to a4 may each independently be 1, 2, 3, or 4, and

at least one selected from R₁ to R₄ may each independently be selectedfrom:

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, and animidazopyrimidinyl group; and

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, and animidazopyrimidinyl group, each substituted with at least one selectedfrom deuterium, —F, —C, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂,a hydroxyl group, a cyano group, a nitro group, an amino group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, animidazopyrimidinyl group, and —Si(Q₃₃)(Q₃₄)(Q₃₅) (wherein Q₃₃ to Q₃₅ areeach independently the same as described herein).

In an embodiment, in Formula 1A, a moiety represented by

may be represented by one selected from Formulae CY1-1 to CY1-16:

In Formulae CY1-1 to CY1-16,

Y₁ may be the same as described herein,

X₁₁ may be N or C-[(L₁₁)_(b11)-(R₁₁)_(c11)], X₁₂ may be N orC-[(L₁₂)_(b12)-(R₁₂)_(c12)], X₁₃ may be N orC-[(L₁₃)_(b13)-(R₁₃)_(c13)], X₁₄ may be N orC-[(L₁₄)_(b14)-(R₁₄)_(c14)], X₁₅ may be N orC-[(L₁₅)_(b15)-(R₁₅)_(c15)], X₁₆ may be N orC-[(L₁₆)_(b16)-(R₁₆)_(c16)], X₁₇ may be N orC-[(L₁₇)_(b17)-(R₁₇)_(c17)], X₁₈ may be N orC-[(L₁₈)_(b18)-(R₁₈)_(c18)],

X₁₉ may be C(R_(19a))(R_(19b)), N-[(L₁₉)_(b19)-(R₁₉)_(c19)], O, S, orSi(R_(19a))(R_(19b)),

L₁₁ to L₁₉ may each independently be the same as described in connectionwith L₁,

b11 to b19 may each independently be the same as described in connectionwith b1,

R₁₁ to R₁₉ and R_(19a) to R_(19c) may each independently be the same asdescribed in connection with R₁,

c11 to c19 may each independently be the same as described in connectionwith c1,

*′ indicates a binding site to M of Formula 1A, and

* indicates a binding site to CY5 of Formula 1A.

In one or more embodiments, in Formula 1A, a moiety represented by

may be represented by one selected from Formulae A1(1) to A1(30):

In Formulae A1(1) to A1(30),

Y₁, L₁, b1, R₁, and c1 may each independently be the same as describedherein,

X₁₉ may be C(R_(19a))(R_(19b)), N-[(L₁₉)_(b19)-(R₁₉)_(c19)], O, S, orSi(R_(19a))(R_(19b)),

L₁₉, b19, and c19 may each independently be the same as described inconnection with L₁, b1, and c1,

R₁₅ to R₁₉ and R_(19a) to R_(19c) may each independently be the same asdescribed in connection with R₁,

a16 may be an integer from 0 to 6,

a15 may be an integer from 0 to 5,

a14 may be an integer from 0 to 4,

a13 may be an integer from 0 to 3,

a12 may be an integer from 0 to 2,

*′ indicates a binding site to M of Formula 1A, and

* indicates a binding site to CY5 of Formula 1A.

In one or more embodiments, in Formula 1A, a moiety represented by

may be represented by one selected from Formulae CY2-1 to CY2-4:

X₅₁ in Formula CY2-1 may be O, S, N-[(L₇)_(b7)-(R₇)_(c7)], C(R₇)(R₈),Si(R₇)(R₈), Ge(R₇)(R₈), or C(═O), X₅₁ in Formulae CY2-2 to CY2-4 may beN, C(R₇), Si(R₇), or Ge(R₇), L₇, b7, R₇, R₆, c7, and c8 may eachindependently be the same as described herein,

in Formulae CY2-1 to CY2-4,

X₂ may be the same as described herein,

X₂₁ may be N or C-[(L₂₁)_(b21)-(R₂₁)_(c21)], X₂₂ may be N orC-[(L₂₂)_(b22)-(R₂₂)_(c22)], X₂₃ may be N orC-[(L₂₃)_(b23)-(R₂₃)_(c23)],

L₂₁ to L₂₃ may each independently be the same as described in connectionwith L₂,

b21 to b23 may each independently be the same as described in connectionwith b2,

R₂₁ to R₂₃ may each independently be the same as described in connectionwith R₂,

c21 to c23 may each independently be the same as described in connectionwith c2,

*′ indicates a binding site to M of Formula 1A,

* indicates a binding site to CY₁ of Formula 1A, and

*″ indicates a binding site to CY₃ of Formula 1A.

In one or more embodiments, in Formula 1A, a moiety represented by

may be represented by one selected from Formulae A2(1) to A2(16):

X₅₁ in Formulae A2(1) to A2(4) may be O, S, N-[(L₇)_(b7)-(R₇)_(c7)],C(R₇)(R₈), Si(R₇)(R₈), Ge(R₇)(R₈), or C(═O), X₅₁ in Formulae A2(5) toA2(16) may be N, C(R₇), Si(R₇), or Ge(R₇), L₇, b7, R₇, R₈, c7, and c8may each independently be the same as described herein,

in Formulae A2(1) to A2(16),

X₂, L₂, b2, R₂, and c2 may each independently be the same as describedherein,

a23 may be an integer from 0 to 3,

a22 may be an integer from 0 to 2,

*′ indicates a binding site to M of Formula 1A,

* indicates a binding site to CY₁ of Formula 1A, and

*″ indicates a binding site to CY₃ of Formula 1A.

In one or more embodiments, in Formula 1A, a moiety represented by

may be represented by one selected from Formulae CY3-1 to CY3-11:

In Formulae CY3-1 to CY3-11,

X₃ may be the same as described herein,

X₃₁ may be N or C-[(L₃₁)_(b31)-(R₃₁)_(c31)], X₃₂ may be N orC-[(L₃₂)_(b32)-(R₃₂)_(c32)], X₃₃ may be N orC-[(L₃₃)_(b33)-(R₃₃)_(c33)], X₃₄ may be N orC-[(L₃₄)_(b34)-(R₃₄)_(c34)], X₃₅ may be N orC-[(L₃₅)_(b35)-(R₃₅)_(c35)], X₃₆ may be N orC-[(L₃₆)_(b36)-(R₃₆)_(c36)], X₃₇ may be N orC-[(L₃₇)_(b37)-(R₃₇)_(c37)],

X₃₉ may be C(R_(39a))(R_(39b)), N-[(L₃₉)_(b39)-(R₃₉)_(c39)], O, S, orSi(R_(39a))(R_(39b)),

L₃₁ to L₃₇ and L₃₉ may each independently be the same as described inconnection with L₃,

b31 to b37 and b39 may each independently be the same as described inconnection with b3,

R₃₁ to R₃₉ and R_(39a) to R_(39b) may each independently be the same asdescribed in connection with R₃,

c31 to c37 and c39 may each independently be the same as described inconnection with c3,

*′ indicates a binding site to M of Formula 1A,

* indicates a binding site to CY4 of Formula 1A, and

*″ indicates a binding site to CY2 of Formula 1A.

In one or more embodiments, in Formula 1A, a moiety represented by

may be represented by one selected from Formulae A3(1) to A3(17):

In Formulae A3(1) to A3(17),

X₃, L₃, b3, R₃, and c3 may each independently be the same as describedherein,

X₃₉ may be C(R_(39a))(R_(39b)), N-[(L₃₉)_(b39)-(R₃₉)_(c39)], O, S, orSi(R_(39a))(R_(39b)),

L₃₉, b39, and c39 may each independently be the same as described inconnection with L₃, b3, and c3,

R₃₁ to R₃₉ and R_(39a) to R_(39b) may each independently be the same asdescribed in connection with R₃,

a35 may be an integer from 0 to 5,

a34 may be an integer from 0 to 4,

a33 may be an integer from 0 to 3,

a32 may be an integer from 0 to 2,

*′ indicates a binding site to M of Formula 1A,

* indicates a binding site to CY₄ of Formula 1A, and

*″ indicates a binding site to CY₂ of Formula 1A.

In one or more embodiments, in Formula 1A, a moiety represented by

may be represented by one selected from Formulae CY4-1 to CY4-16:

In Formulae CY4-1 to CY4-16,

X₄ may be the same as described herein,

X₄₁ may be N or C-[(L₄₁)_(b41)-(R₄₁)_(c41)], X₄₂ may be N orC-[(L₄₂)_(b42)-(R₄₂)_(c42)], X₄₃ may be N orC-[(L₄₃)_(b43)-(R₄₃)_(c43)], X₄₄ may be N orC-[(L₄₄)_(b44)-(R₄₄)_(c44)], X₄₅ may be N orC-[(L₄₅)_(b45)-(R₄₅)_(c45)], X₄₆ may be N orC-[(L₄₆)_(b46)-(R₄₆)_(c46)], X₄₇ may be N orC-[(L₄₇)_(b47)-(R₄₇)_(c47)], X₄₈ may be N orC-[(L₄₈)_(b48)-(R₄₈)_(c48)],

X₄₉ may be C(R_(49a))(R_(49b)), N-[(L₄₉)_(b49)-(R₄₉)_(c49)], O, S, orSi(R_(49a))(R_(49b)),

L41 to L49 may each independently be the same as described in connectionwith L₄,

b41 to b49 may each independently be the same as described in connectionwith b4,

R₄₁ to R₄₉ and R_(49a) to R_(49c) may each independently be the same asdescribed in connection with R₄,

c41 to c49 may each independently be the same as described in connectionwith c4,

*′ indicates a binding site to M of Formula 1A, and

* indicates a binding site to CY₃ of Formula 1A.

In one or more embodiments, in Formula 1A, a moiety represented by

may be represented by one selected from Formulae A4(1) to A4(45):

In Formulae A4(1) to A4(45),

X₄, L₄, b4, R₄, and c4 may each independently be the same as describedherein,

X₄₉ may be C(R_(49a))(R_(49b)), N-[(L₄₉)_(b49)-(R₄₉)_(c49)], O, S, orSi(R_(49a))(R_(49b)),

L₄₉, b49, and c49 may each independently be the same as described inconnection L₄, b4, and c4,

R₄₅ to R₄₉ and R_(49a) to R_(49c) may each independently be the same asdescribed in connection R₄,

a46 may be an integer from 0 to 6,

a45 may be an integer from 0 to 5,

a44 may be an integer from 0 to 4,

a43 may be an integer from 0 to 3,

a42 may be an integer from 0 to 2,

*′ indicates a binding site to M of Formula 1A, and

* indicates a binding site to CY₃ of Formula 1A.

In one or more embodiments, in Formula 1A, a moiety represented by

may be represented by one selected from Formulae CY1(1) to CY1(8),and/or a moiety represented by

may be represented by one selected from Formulae CY2(1) to CY2(4),and/or a moiety represented by

may be represented by one selected from Formulae CY3(1) to CY3(24),and/or a moiety represented by

may be represented by one selected from Formulae CY4(1) to CY4(67):

X₅₁ in Formulae CY2(1) to CY2(4) may be O, S, N-[(L₇)_(b7)-(R₇)_(c7)],C(R₇)(R₈), Si(R₇)(R₈), Ge(R₇)(R₈), or C(═O), L₇, b7, R₇, R₈, c7, and c8may each independently be the same as described herein,

in Formulae CY1(1) to CY1(8), Formulae CY2(1) to CY2(4), Formulae CY3(1)to CY3(24), and Formulae CY4(1) to CY4(67),

X₂ to X₄, Y₁, L₁ to L₄, b1 to b4, R₁ to R₄, and c1 to c4 may eachindependently be the same as described herein,

X₃₉ may be C(R_(39a))(R_(39b)), N-[(L₃₉)_(b39)-(R₃₉)_(c39)], O, S, orSi(R_(39a))(R_(39b)),

X₄₉ may be C(R_(49a))(R_(49b)), N-[(L₄₉)_(b49)-(R₄₉)_(c49)], O, S, orSi(R_(49a))(R_(49b)),

L_(1a) and L_(1b) may each independently be the same as described inconnection with L₁,

R_(1a) and R_(1b) may each independently be the same as described inconnection with R₁,

L_(3a), L_(3b), and L₃₉ may each independently be the same as describedin connection with L₃,

R_(3a), R_(3b), R₃₉, R_(39a), and R_(39b) may each independently be thesame as described in connection with R₃,

b39 and c39 may each independently be the same as described inconnection with b3 and c3,

L₄a, L_(4b), and L₄₉ may each independently be the same as described inconnection with L₄,

R_(4a), R_(4b), R₄₉, R_(49a), and R_(49b) may each independently be thesame as described in connection with R₄,

b49 and c49 may each independently be the same as described inconnection with b4 and c4,

*-(L₁)_(b1)-(R₁)_(c1), *-(L_(1a))_(b1)-(R_(1a))_(c1),*-(L_(1b))_(b1)-(R_(1b))_(c1), *-(L₂)_(b2)-(R₂)_(c2),*-(L₃)_(b3)-(R₃)_(c3), *-(L_(3a))_(b3)-(R_(3a))_(c3),*-(L_(3b))_(b3)-(R_(3b))_(c3), *-(L₄)_(b4)-(R₄)_(c4),*-(L_(4a))_(b4)-(R_(4a))_(c4), and *-(L_(4b))_(b4)-(R_(4b))_(c4) mayeach not be hydrogen, wherein * indicates a bonding site to aneighboring atom,

in Formulae CY1(1) to CY1(8), Formulae CY2(1) to CY2(4), Formulae CY3(1)to CY3(24), and Formulae CY4(1) to CY4(67), *′ indicates a binding siteto M of Formula 1A,

in Formulae CY1(1) to CY1(8), * indicates a binding site to CY₅ ofFormula 1A,

in Formulae CY2(1) to CY2(4), * indicates a binding site to CY₁ ofFormula 1A and indicates a binding site to CY₃ of Formula 1A,

in Formulae CY3(1) to CY3(24), *″ indicates a binding site to CY₂ ofFormula 1A and * indicates a binding site to CY₄ of Formula 1A, and

in Formulae CY4(1) to CY4(67), * indicates a binding site to CY₃ ofFormula 1A.

In one or more embodiments, the organometallic compound may berepresented by Formula 1:

In Formula 1,

M, X₁ to X₄, Y₁, Y₃ to Y₅, CY₁ to CY₅, X₅₁ (wherein X₅₁ in Formula 1 isnot N, C(R₇), Si(R₇), or Ge(R₇)), 1 to L₄, L₇, b1 to b4, b7, R₁ to R₄,c1 to c4, and a1 to a4 may each independently be the same as describedherein,

Y₂, Y₆ to Y₉ may each independently be N or C,

Y₁₀ and Y₁₁ may each independently be C, N, O, or S, and

a bond between Y₁ and Y₁₀, a bond between Y₁ and Y₂, a bond between X₂and Y₃, a bond between X₂ and Y₄, a bond between Y₄ and Y₅, a bondbetween Y₄ and Y₆, a bond between X₃ and Y₇, a bond between X₃ and Y₈, abond between X₄ and Y₉, and a bond between X₄ and Y₁₁ may eachindependently be a single bond or a double bond, and a bond between Y₂and Y₃, a bond between Y₆ and Y₇, and a bond between Y₈ and Y₉ may eachbe a single bond.

In one or more embodiments, the organometallic compound may berepresented by Formula 1-1:

In Formula 1-1,

M, X₁ to X₃, and X₅₁ may each independently be the same as describedherein,

X₁₁ may be N or C-[(L₁₁)_(b11)-(R₁₁)_(c11)], X₁₂ may be N orC-[(L₁₂)_(b12)-(R₁₂)_(c12)], X₁₃ may be N orC-[(L₁₃)_(b13)-(R₁₃)_(c13)], X₁₄ may be N orC-[(L₁₄)_(b14)-(R₁₄)_(c14)],

L₁₁ to L₁₄, b11 to b14, R₁₁ to R₁₄ and c11 to c14 may each independentlybe the same as described in connection with L₁, b1, R₁, and c1,

X₂₁ may be N or C-[(L₂₁)_(b21)-(R₂₁)_(c21)], X₂₂ may be N orC-[(L₂₂)_(b22)-(R₂₂)_(c22)], X₂₃ may be N orC-[(L₂₃)_(b23)-(R₂₃)_(c23)],

L₂₁ to L₂₃, b21 to b23, R₂₁ to R₂₃ and c21 to c23 may each independentlybe the same as described in connection with L₂, b2, R₂, and c2,

X₃₁ may be N or C-[(L₃₁)_(b31)-(R₃₁)_(c31)], X₃₂ may be N orC-[(L₃₂)_(b32)-(R₃₂)_(c32)], X₃₃ may be N orC-[(L₃₃)_(b33)-(R₃₃)_(c33)],

L₃₁ to L₃₃, b31 to b33, R₃₁ to R₃₃ and c31 to c33 may each independentlybe the same as described in connection with L₃, b3, R₃, and c3,

X₄₁ may be N or C-[(L₄₁)_(b41)-(R₄₁)_(c41)], X₄₂ may be N orC-[(L₄₂)_(b42)-(R₄₂)_(c42)], X₄₃ may be N orC-[(L₄₃)_(b43)-(R₄₃)_(c43)], X₄₄ may be N orC-[(L₄₄)_(b44)-(R₄₄)_(c44)],

L₄₁ to L₄₄, b41 to b44, R₄₁ to R₄₄ and c41 to c44 may each independentlybe the same as described in connection with L₄, b4, R₄, and c4,

two of R₁₁ to R₁₄ may optionally be linked to form a substituted orunsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstitutedC₁-C₃₀ heterocyclic group,

two of R₂₁ to R₂₃ may optionally be linked to form a substituted orunsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstitutedC₁-C₃₀ heterocyclic group,

two of R₃₁ to R₃₃ may optionally be linked to form a substituted orunsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstitutedC₁-C₃₀ heterocyclic group, and

two of R₄₁ to R₄₄ may optionally be linked to form a substituted orunsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstitutedC₁-C₃₀ heterocyclic group.

For example, in Formula 1-1, i) a substituted or unsubstituted C₅-C₃₀carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclicgroup, formed by linking two of R₁₁ to R₁₄, ii) a substituted orunsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstitutedC₁-C₃₀ heterocyclic group, formed by linking two of R₂₁ to R₂₃, iii) asubstituted or unsubstituted C₅-C₃₀ carbocyclic group or a substitutedor unsubstituted C₁-C₃₀ heterocyclic group, formed by linking two of R₃₁to R₃₂, iv) a substituted or unsubstituted C₅-C₃₀ carbocyclic group or asubstituted or unsubstituted C₁-C₃₀ heterocyclic group, formed bylinking two of R₄₁ to R₄₄, and v) a substituted or unsubstituted C₅-C₃₀carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclicgroup, formed by linking two or more neighboring groups selected fromR₁₁ to R₁₄, R₂₁ to R₂₃, R₃₁ to R₃₃, and R₄₁ to R₄₄ may eachindependently be selected from:

a cyclopentadiene group, a cyclohexane group, a cycloheptane group, anadamantane group, a norbornane group, a norbornene group, abicycle-heptane group, a bicyclo-octane group, a benzene group, apyridine group, a pyrimidine group, a pyrazine group, a pyridazinegroup, a triazine group, a naphthalene group, an anthracene group, atetracene group, a phenanthrene group, a dihydronaphthalene group, aphenalene group, a benzothiophene group, a benzofuran group, an indenegroup, an indole group, a benzosilole group, an azabenzothiophene group,an azabenzofuran group, an azaindene group, an azaindole group, and anazabenzosilole group; and

a cyclopentadiene group, a cyclohexane group, a cycloheptane group, anadamantane group, a norbornane group, a norbornene group, abicycle-heptane group, a bicyclo-octane group, a benzene group, apyridine group, a pyrimidine group, a pyrazine group, a pyridazinegroup, a triazine group, a naphthalene group, an anthracene group, atetracene group, a phenanthrene group, a dihydronaphthalene group, aphenalene group, a benzothiophene group, a benzofuran group, an indenegroup, an indole group, a benzosilole group, an azabenzothiophene group,an azabenzofuran group, an azaindene group, an azaindole group, and anazabenzosilole group, each substituted with at least one R_(1a),

but embodiments of the present disclosure are not limited thereto.

R_(1a) may be the same as described in connection with R₁.

For example, the organometallic compound may be represented by Formula1-1, and in Formula 1-1,

X₁₁ may be C-[(L₁₁)_(b11)-(R₁₁)_(c11)], X₁₂ may beC-[(L₁₂)_(b12)-(R₁₂)_(c12)], X₁₃ may be C-[(L₁₃)_(b13)-(R₁₃)_(c13)], X₁₄may be C-[(L₁₄)_(b14)-(R₁₄)_(c14)], X₂₁ may beC-[(L₂₁)_(b21)-(R₂₁)_(c21)], X₂₂ may be C-[(L₂₂)_(b22)-(R₂₂)_(c22)], X₂₃may be C-[(L₂₃)_(b23)-(R₂₃)_(c23)], X₃₁ may beC-[(L₃₁)_(b31)-(R₃₁)_(c31)], X₃₂ may be C-[(L₃₂)_(b32)-(R₃₂)_(c32)], X₃₃may be C-[(L₃₃)_(b33)-(R₃₃)_(c33)], X₄₁ may beC-[(L₄₁)_(b41)-(R₄₁)_(c41)], X₄₂ may be C-[(L₄₂)_(b42)-(R₄₂)_(c42)], X₄₃may be C-[(L₄₃)_(b43)-(R₄₃)_(c43)], X₄₄ may beC-[(L₄₄)_(b44)-(R₄₄)_(c44)],

X₅₁ may be O, S, or N-[(L₇)_(b7)-(R₇)_(c7)],

b7 may be 0, c7 may be 1,

R₇ may be selected from:

a C₁-C₃₀ alkyl group; and

a C₁-C₃₀ alkyl group substituted with at least one selected fromdeuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl group, a norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinylgroup, and

at least one selected from R₁₁ to R₁₄, R₂₁ to R₂₃, R₃₁ to R₃₃, and R₄₁to R₄₄ may be selected from:

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, and animidazopyrimidinyl group; and

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, and animidazopyrimidinyl group, each substituted with at least one selectedfrom deuterium, —F, —C, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂,a hydroxyl group, a cyano group, a nitro group, an amino group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, an adamantanyl group, a norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a dibenzosilolyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, animidazopyrimidinyl group, and —Si(Q₃₃)(Q₃₄)(Q₃₅) (wherein Q₃₃ to Q₃₅ areeach independently the same as described herein),

but embodiments of the present disclosure are not limited thereto.

In one or more embodiments the organometallic compound may berepresented by Formula 1-1, and in Formula 1-1,

X₁₁ may be C-[(L₁₁)_(b11)-(R₁₁)_(c11)], X₁₂ may beC-[(L₁₂)_(b12)-(R₁₂)_(c12)], X₁₃ may be C-[(L₁₃)_(b13)-(R₁₃)_(c13)], X₁₄may be C-[(L₁₄)_(b14)-(R₁₄)_(c14)], X₂₁ may beC-[(L₂₁)_(b21)-(R₂₁)_(c21)], X₂₂ may be C-[(L₂₂)_(b22)-(R₂₂)_(c22)], X₂₃may be C-[(L₂₃)_(b23)-(R₂₃)_(c23)], X₃₁ may beC-[(L₃₁)_(b31)-(R₃₁)_(c31)], X₃₂ may be C-[(L₃₂)_(b32)-(R₃₂)_(c32)], X₃₃may be C-[(L₃₃)_(b33)-(R₃₃)_(c33)], X₄₁ may beC-[(L₄₁)_(b41)-(R₄₁)_(c41)], X₄₂ may be C-[(L₄₂)_(b42)-(R₄₂)_(c42)], X₄₃may be C-[(L₄₃)_(b43)-(R₄₃)_(c43)], X₄₄ may beC-[(L₄₄)_(b44)-(R₄₄)_(c44)],

X₅₁ may be O, S, or N-[(L₇)_(b7)-(R₇)_(c7)],

b7 may be 0, c7 may be 1,

R₇ may be selected from:

a C₁-C₃₀ alkyl group; and

a C₁-C₃₀ alkyl group substituted with at least one selected fromdeuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl group, a norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinylgroup,

R₁₁ to R₁₄, R₂₁ to R₂₃, R₃₁ to R₃₃, and R₄₁ to R₄₄ may eachindependently be selected from hydrogen, deuterium, —F, a cyano group, anitro group, —SF₅, —CH₃, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, groupsrepresented by Formulae 9-1 to 9-19, groups represented by Formulae 10-1to 10-167, —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉)(wherein Q₁ to Q₉ are each independently the same as described herein),and

in Formula 1-1, at least one selected from R₁₁ to R₁₄, R₂₁ to R₂₃, R₃₁to R₃₃, and R₄₁ to R₄₄ may each independently be selected from groupsrepresented by Formulae 10-1 to 10-167, but embodiments of the presentdisclosure are not limited thereto.

For example, the organometallic compound may be one selected fromCompounds 1-1 to 1-88, Compounds 2-1 to 2-47, and Compounds 3-1 to3-582, but embodiments of the present disclosure are not limitedthereto:

Formula 1A includes a5-membered ring represented by CY₅, Formula 1Aincludes a cyclometallated ring formed by CY₅, CY₂, CY₃, and Min Formula1A which is a6-membered ring (see Formula 1A′). Accordingly, a stablebond angle may be formed between a tetradentate ligand and a metal inFormula 1A, thereby improving a molecular stability of theorganometallic compound represented by Formula 1A:

In addition, in Formula 1A, in cases where i) M is Pt, ii) X₁ is O, iii)X₂ and X₄ are each N, X₃ is C, a bond between X₂ and M and a bondbetween X₄ and M are each a coordinate bond, and a bond between X₃ and Mis a covalent bond, iv) Y₁ to Y₅ are each C, v) a bond between Y₅ andX₅₁ and a bond between Y₃ and X₅₁ are each a single bond, vi) CY₁, CY₂,and CY₃ are each a benzene group, and CY₄ is a pyridine group, vii) X₅₁is O, S, or N-[(L₇)_(b7)-(R₇)_(c7)], and viii) b7 is 0, c7 is 1, and R₇is a substituted or unsubstituted C₁-C₆₀ alkyl group, a1 to a4 may eachindependently be 1, 2, 3, 4, or 5, and at least one selected from R₁ toR₄ may be selected from a substituted or unsubstituted C₃-C₁₀ cycloalkylgroup, a substituted or unsubstituted C₁-C₆₀ heterocycloalkyl group, asubstituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted orunsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted orunsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₁-C₆₀heteroaryl group, a substituted or unsubstituted monovalent non-aromaticcondensed polycyclic group, and a substituted or unsubstitutedmonovalent non-aromatic condensed heteropolycyclic group. Thus, theorganometallic compound represented by Formula 1A may have improvedmolecular orientation, and in this regard, an electronic device, forexample, an organic light-emitting device, which includes theorganometallic compound represented by Formula 1A, may have improvedefficiency and lifespan.

X₄ in Formula 1A may be N. Thus, the organometallic compound representedby Formula 1A may emit a phosphorescent light emission having a highluminescent efficiency due to a intermolecular charge transfermechanism.

Furthermore, CY₄ in Formula 1A may not be a benzimidazole group. In anembodiment, CY₄ in Formula 1A may be selected from a) 6-membered ring,b) a condensed ring having two or more 6-membered rings that arecondensed to each other, and c) a condensed ring having two or more6-membered rings and one 5-membered ring that are condensed to eachother, wherein the 6-membered ring may be selected from a cyclohexanegroup, a cyclohexene group, an adamantane group, a norbornane group, anorbornene group, a benzene group, a pyridine group, a pyrimidine group,a pyrazine group, a pyridazine group, and a triazine group, and the5-membered ring may be selected from a cyclopentane group, acyclopentene group, a cyclopentadiene group, a furan group, a thiophenegroup, a silole group, a pyrrole group, a pyrazole group, an imidazolegroup, a triazole group, an oxazole group, an isooxazole group, athiazole group, an isothiazole group, an oxadiazole group, and athiadiazole group. Thus, the organometallic compound represented byFormula 1A may emit a phosphorescent light emission having a highluminescent efficiency due to an intermolecular charge transfermechanism.

For example, a highest occupied molecular orbital (HOMO) energy level, alowest unoccupied molecular orbital (LUMO) energy level, a singlet (S₁)energy level, and a triplet (T₁) energy level of each of Compounds 1-28,1-30, 1-17, 1-9, and 1-12 were evaluated by using a density functionaltheory (DFT) method of a Gaussian program (a structure was optimized ata B3LYP, 6-31G(d,p) level). Evaluation results thereof are shown inTable 1.

TABLE 1 Compound HOMO LUMO S₁ energy level T₁ energy level No. (eV) (eV)(eV) (eV) 1-28 −4.869 −1.589 2.728 2.472 1-30 −4.994 −1.793 2.661 2.4391-17 −4.794 −1.528 2.721 2.47  1-9  −4.782 −1.528 2.719 2.466 1-12−4.813 −1.598 2.693 2.395

Referring to Table 1, it has been determined that the organometalliccompound represented by Formula 1A has electrical characteristicssuitable for use as a dopant of an electronic device, for example, anorganic light-emitting device.

Synthesis methods of the organometallic compound represented by Formula1A may be recognizable by one of ordinary skill in the art by referringto Synthesis Examples provided below.

The organometallic compound represented by Formula 1A is suitable foruse in an organic layer of an organic light-emitting device, forexample, for use as a dopant in an emission layer of the organic layer.Thus, another aspect of the present disclosure provides an organiclight-emitting device that includes: a first electrode; a secondelectrode; and an organic layer that is disposed between the firstelectrode and the second electrode and includes an emission layer,wherein the organic layer includes at least one of the organometalliccompound represented by Formula 1A.

The organic light-emitting device may have, due to the inclusion of anorganic layer including the organometallic compound represented byFormula 1A, a low driving voltage, high efficiency, high power, highquantum efficiency, a long lifespan, a low roll-off ratio, and excellentcolor purity.

The organometallic compound represented by Formula 1A may be usedbetween a pair of electrodes of an organic light-emitting device. Forexample, the organometallic compound represented by Formula 1A may beincluded in the emission layer. In this regard, the organometalliccompound may act as a dopant, and the emission layer may further includea host (that is, an amount of the organometallic compound represented byFormula 1A is smaller than an amount of the host).

The expression “(an organic layer) includes at least one oforganometallic compounds” as used herein may include an embodiment inwhich “(an organic layer) includes identical organometallic compoundsrepresented by Formula 1A” and an embodiment in which “(an organiclayer) includes two or more different organometallic compoundsrepresented by Formula 1A.”

For example, the organic layer may include, as the organometalliccompound, only Compound 1-1. In this regard, Compound 1-1 may beincluded in an emission layer of the organic light-emitting device. Inone or more embodiments, the organic layer may include, as theorganometallic compound, Compound 1-1 and Compound 1-2. In this regard,Compound 1-1 and Compound 1-2 may be included in an identical layer (forexample, Compound 1-1 and Compound 1-2 all may be included in anemission layer).

The first electrode may be an anode, which is a hole injectionelectrode, and the second electrode may be a cathode, which is anelectron injection electrode, or the first electrode may be a cathode,which is an electron injection electrode, and the second electrode maybe an anode, which is a hole injection electrode.

For example, in the organic light-emitting device, the first electrodemay be an anode, and the second electrode may be a cathode, and theorganic layer may further include a hole transport region disposedbetween the first electrode and the emission layer and an electrontransport region disposed between the emission layer and the secondelectrode, and the hole transport region may include a hole injectionlayer, a hole transport layer, an electron blocking layer, or anycombination thereof, and the electron transport region may include ahole blocking layer, an electron transport layer, an electron injectionlayer, or any combination thereof.

The term “organic layer” as used herein refers to a single layer and/ora plurality of layers disposed between the first electrode and thesecond electrode of the organic light-emitting device. The “organiclayer” may include, in addition to an organic compound, anorganometallic complex including metal.

The FIGURE is a schematic view of an organic light-emitting device 10according to an embodiment. Hereinafter, the structure of an organiclight-emitting device according to an embodiment and a method ofmanufacturing an organic light-emitting device according to anembodiment will be described in connection with the FIGURE. The organiclight-emitting device 10 includes a first electrode 11, an organic layer15, and a second electrode 19, which are sequentially stacked.

A substrate may be additionally disposed under the first electrode 11 orabove the second electrode 19. For use as the substrate, any substratethat is used in general organic light-emitting devices may be used, andthe substrate may be a glass substrate or a transparent plasticsubstrate, each having excellent mechanical strength, thermal stability,transparency, surface smoothness, ease of handling, and waterresistance.

The first electrode 11 may be formed by depositing or sputtering amaterial for forming the first electrode 11 on the substrate. The firstelectrode 11 may be an anode. The material for forming the firstelectrode 11 may be selected from materials with a high work function tofacilitate hole injection. The first electrode 11 may be a reflectiveelectrode, a semi-transmissive electrode, or a transmissive electrode.The material for forming the first electrode may be, for example, indiumtin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO₂), and zincoxide (ZnO). In one or more embodiments, magnesium (Mg), aluminum (Al),aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), ormagnesium-silver (Mg—Ag) may be used as the material for forming thefirst electrode.

The first electrode 11 may have a single-layered structure or amulti-layered structure including two or more layers. For example, thefirst electrode 11 may have a three-layered structure of ITO/Ag/ITO, butthe structure of the first electrode 110 is not limited thereto.

The organic layer 15 is disposed on the first electrode 11.

The organic layer 15 may include a hole transport region, an emissionlayer, and an electron transport region.

The hole transport region may be disposed between the first electrode 11and the emission layer.

The hole transport region may include a hole injection layer, a holetransport layer, an electron blocking layer, a buffer layer, or anycombination thereof.

The hole transport region may include only either a hole injection layeror a hole transport layer. In one or more embodiments, the holetransport region may have a hole injection layer/hole transport layerstructure or a hole injection layer/hole transport layer/electronblocking layer structure, which are sequentially stacked in this statedorder from the first electrode 11.

A hole injection layer may be formed on the first electrode 11 by usingone or more suitable methods selected from vacuum deposition, spincoating, casting, or Langmuir-Blodgett (LB) deposition.

When a hole injection layer is formed by vacuum deposition, thedeposition conditions may vary according to a compound that is used toform the hole injection layer, and the structure and thermalcharacteristics of the hole injection layer. For example, the depositionconditions may include a deposition temperature of about 100° C. toabout 500° C., a vacuum pressure of about 10⁻⁸ torr to about 10⁻³ torr,and a deposition rate of about 0.01 Angstroms per second (A/sec) toabout 100 Å/sec. However, the deposition conditions are not limitedthereto.

When the hole injection layer is formed using spin coating, coatingconditions may vary according to the material used to form the holeinjection layer, and the structure and thermal properties of the holeinjection layer. For example, a coating speed may be from about 2,000revolutions per minute (rpm) to about 5,000 rpm, and a temperature atwhich a heat treatment is performed to remove a solvent after coatingmay be from about 80° C. to about 200° C. However, the coatingconditions are not limited thereto.

Conditions for forming a hole transport layer and an electron blockinglayer may be understood by referring to conditions for forming the holeinjection layer.

The hole transport region may include at least one selected fromm-MTDATA, TDATA, 2-TNATA, NPB, β-NPB, TPD, spiro-TPD, spiro-NPB,methylated-NPB, TAPC, HMTPD, 4,4′,4″-tris(N-carbazolyl)triphenylamine(TCTA), polyaniline/dodecylbenzene sulfonic acid (PANI/DBSA),poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonate) (PEDOT/PSS),polyaniline/camphor sulfonic acid (PANI/CSA), polyaniline/poly(4-styrenesulfonate) (PANI/PSS), a compound represented by Formula 201 below, anda compound represented by Formula 202 below:

In Formula 201, Ar₁₀₁ and Ar₁₀₂ may each independently be selected from:

a phenylene group, a pentalenylene group, an indenylene group, anaphthylene group, an azulenylene group, a heptalenylene group, anacenaphthylene group, a fluorenylene group, a phenalenylene group, aphenanthrenylene group, an anthracenylene group, a fluoranthenylenegroup, a triphenylenylene group, a pyrenylene group, a chrysenylenylenegroup, a naphthacenylene group, a picenylene group, a perylenylenegroup, and a pentacenylene group; and

a phenylene group, a pentalenylene group, an indenylene group, anaphthylene group, an azulenylene group, a heptalenylene group, anacenaphthylene group, a fluorenylene group, a phenalenylene group, aphenanthrenylene group, an anthracenylene group, a fluoranthenylenegroup, a triphenylenylene group, a pyrenylene group, a chrysenylenylenegroup, a naphthacenylene group, a picenylene group, a perylenylenegroup, and a pentacenylene group, each substituted with at least oneselected from deuterium, —F, —C, —Br, —I, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynylgroup, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroarylgroup, a C₂-C₆₀ heteroaryloxy group, a C₂-C₆₀ heteroarylthio group, aC₃-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensedpolycyclic group, and a monovalent non-aromatic condensedheteropolycyclic group.

In Formula 201, xa and xb may each independently be an integer from 0 to5, or may each independently be 0, 1, or 2. For example, xa may be 1 andxb may be 0, but embodiments of the present disclosure are not limitedthereto.

In Formulae 201 and 202, R₁₀₁ to R₁₀₈, R₁₁₁ to R₁₁₉, and R₁₂₁ to R₁₂₄may each independently be selected from:

hydrogen, deuterium, —F, —C, —Br, —I, a hydroxyl group, a cyano group, anitro group, an amino group, an amidino group, a hydrazine group, ahydrazone group, a carboxylic acid group or a salt thereof, a sulfonicacid group or a salt thereof, a phosphoric acid group or a salt thereof,a C₁-C₁₀ alkyl group (for example, a methyl group, an ethyl group, apropyl group, a butyl group, pentyl group, a hexyl group, and the like),and a C₁-C₁₀ alkoxy group (for example, a methoxy group, an ethoxygroup, a propoxy group, a butoxy group, a pentoxy group, and the like);

a C₁-C₁₀ alkyl group and a C₁-C₁₀ alkoxy group, each substituted with atleast one selected from deuterium, —F, —C, —Br, —I, a hydroxyl group, acyano group, a nitro group, an amino group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, and a phosphoric acidgroup or a salt thereof;

a phenyl group, a naphthyl group, an anthracenyl group, a fluorenylgroup, and a pyrenyl group; and

a phenyl group, a naphthyl group, an anthracenyl group, a fluorenylgroup, and a pyrenyl group, each substituted with at least one selectedfrom deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, anitro group, an amino group, an amidino group, a hydrazine group, ahydrazone group, a carboxylic acid group or a salt thereof, a sulfonicacid group or a salt thereof, a phosphoric acid group or a salt thereof,a C₁-C₁₀ alkyl group, and a C₁-C₁₀ alkoxy group;

but embodiments of the present disclosure are not limited thereto.

In Formula 201, R₁₀₉ may be selected from:

a phenyl group, a naphthyl group, an anthracenyl group, and a pyridinylgroup; and

a phenyl group, a naphthyl group, an anthracenyl group, and a pyridinylgroup, each substituted with at least one selected from deuterium, —F,—C, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an aminogroup, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkylgroup, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, ananthracenyl group, and a pyridinyl group.

In an embodiment, the compound represented by Formula 201 may berepresented by Formula 201A, but embodiments of the present disclosureare not limited thereto:

In Formula 201A, R₁₀₁, R₁₁₁, R₁₁₂, and R₁₀₉ may be understood byreferring to the description provided herein.

For example, the compound represented by Formula 201, and the compoundrepresented by Formula 202 may include Compounds HT1 to HT20 below, butembodiments of the present disclosure are not limited thereto:

A thickness of the hole transport region may be in a range of about 100Angstroms (Å) to about 10,000 Å, for example, about 100 Å to about 1,000Å. When the hole transport region includes at least one of a holeinjection layer and a hole transport layer, the thickness of the holeinjection layer may be in a range of about 100 Å to about 10,000 Å, andfor example, about 100 Å to about 1,000 Å, and the thickness of the holetransport layer may be in a range of about 50 Å to about 2,000 Å, andfor example, about 100 Å to about 1,500 Å. While not wishing to be boundby theory, it is understood that when the thicknesses of the holetransport region, the hole injection layer, and the hole transport layerare within these ranges, satisfactory hole transporting characteristicsmay be obtained without a substantial increase in driving voltage.

The hole transport region may further include, in addition to thesematerials, a charge-generation material for the improvement ofconductive properties. The charge-generation material may behomogeneously or non-homogeneously dispersed in the hole transportregion.

The charge-generation material may be, for example, a p-dopant. Thep-dopant may be one selected from a quinone derivative, a metal oxide,and a cyano group-containing compound, but embodiments of the presentdisclosure are not limited thereto. Non-limiting examples of thep-dopant are a quinone derivative, such as tetracyanoquinonedimethane(TCNQ) or 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinonedimethane(F4-TCNQ); a metal oxide, such as a tungsten oxide or a molybdeniumoxide; and a cyano group-containing compound, such as Compound HT-D1 orCompound HT-D2 below, but embodiments of the present disclosure are notlimited thereto:

The hole transport region may include a buffer layer.

The buffer layer may compensate for an optical resonance distanceaccording to a wavelength of light emitted from the emission layer, andthus, efficiency of a formed organic light-emitting device may beimproved.

Then, an emission layer may be formed on the hole transport region byvacuum deposition, spin coating, casting, LB deposition, or the like.When the emission layer is formed by vacuum deposition or spin coating,the deposition or coating conditions may be similar to those applied informing the hole injection layer although the deposition or coatingconditions may vary according to a material that is used to form theemission layer.

Meanwhile, when the hole transport region includes an electron blockinglayer, a material for the electron blocking layer may be selected frommaterials for the hole transport region described above and materialsfor a host to be explained later. However, the material for the electronblocking layer is not limited thereto. For example, when the holetransport region includes an electron blocking layer, a material for theelectron blocking layer may be mCP, which will be explained later.

The emission layer may include a host and a dopant, and the dopant mayinclude the organometallic compound represented by Formula 1A.

The host may include at least one selected from TPBi, TBADN, ADN (alsoreferred to as “DNA”), CBP, CDBP, TCP, mCP, Compound H50, and CompoundH51:

In one or more embodiments, the host may further include a compoundrepresented by Formula 301 below:

In Formula 301, Ar₁₁₁ and Ar₁₁₂ may each independently be selected from:

a phenylene group, a naphthylene group, a phenanthrenylene group, and apyrenylene group; and

a phenylene group, a naphthylene group, a phenanthrenylene group, and apyrenylene group, each substituted with at least one selected from aphenyl group, a naphthyl group, and an anthracenyl group.

In Formula 301, Ar₁₁₃ to Ar₁₁ may each independently be selected from:

a C₁-C₁₀ alkyl group, a phenyl group, a naphthyl group, a phenanthrenylgroup, and a pyrenyl group; and

a phenyl group, a naphthyl group, a phenanthrenyl group, and a pyrenylgroup, each substituted with at least one selected from a phenyl group,a naphthyl group, and an anthracenyl group.

In Formula 301, g, h, i, and j may each independently be an integer from0 to 4, for example, 0, 1, or 2.

In Formula 301, Ar₁₁₃ to Ar₁₁₆ may each independently be selected from:

a C₁-C₁₀ alkyl group substituted with at least one selected from aphenyl group, a naphthyl group, and an anthracenyl group;

a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group,a phenanthrenyl group, and a fluorenyl group;

a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group,a phenanthrenyl group, and a fluorenyl group, each substituted with atleast one selected from deuterium, —F, —C, —Br, —I, a hydroxyl group, acyano group, a nitro group, an amino group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, aC₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a phenyl group, a naphthylgroup, an anthracenyl group, a pyrenyl group, a phenanthrenyl group, anda fluorenyl group; and

but embodiments of the present disclosure are not limited thereto.

In one or more embodiments, the host may include a compound representedby Formula 302:

In Formula 302, Ar₁₂₂ to Ar₁₂₅ are the same as described in detail inconnection with Ar₁₁₃ in Formula 301.

In Formula 302, Ar₁₂₆ and Ar₁₂₇ may each independently be a C₁-C₁₀ alkylgroup (for example, a methyl group, an ethyl group, or a propyl group).

In Formula 302, k and l may each independently be an integer from 0 to4. For example, k and l may be 0, 1, or 2.

The compound represented by Formula 301 and the compound represented byFormula 302 may include Compounds H1 to H42 below, but embodiments ofthe present disclosure are not limited thereto.

When the organic light-emitting device is a full-color organiclight-emitting device, the emission layer may be patterned into a redemission layer, a green emission layer, and a blue emission layer. Inone or more embodiments, due to a stacked structure including a redemission layer, a green emission layer, and/or a blue emission layer,the emission layer may emit white light.

When the emission layer includes a host and a dopant, an amount of thedopant may be in a range of about 0.01 parts by weight to about 15 partsby weight based on 100 parts by weight of the host, but embodiments ofthe present disclosure are not limited thereto.

A thickness of the emission layer may be in a range of about 100 Å toabout 1,000 Å, for example, about 200 Å to about 600 Å. While notwishing to be bound by theory, it is understood that when the thicknessof the emission layer is within this range, excellent light-emissioncharacteristics may be obtained without a substantial increase indriving voltage.

Then, an electron transport region may be disposed on the emissionlayer.

The electron transport region may include a hole blocking layer, anelectron transport layer, an electron injection layer, or anycombination thereof.

For example, the electron transport region may have a hole blockinglayer/electron transport layer/electron injection layer structure or anelectron transport layer/electron injection layer structure, but thestructure of the electron transport region is not limited thereto. Theelectron transport layer may have a single-layered structure or amulti-layered structure including two or more different materials.

Conditions for forming the hole blocking layer, the electron transportlayer, and the electron injection layer which constitute the electrontransport region may be understood by referring to the conditions forforming the hole injection layer.

When the electron transport region includes a hole blocking layer, thehole blocking layer may include, for example, at least one of BCP,Bphen, and BAlq but embodiments of the present disclosure are notlimited thereto:

A thickness of the hole blocking layer may be in a range of about 20 Åto about 1,000 Å, for example, about 30 Å to about 300 Å. While notwishing to be bound by theory, it is understood that when the thicknessof the hole blocking layer is within these ranges, the hole blockinglayer may have improved hole blocking ability without a substantialincrease in driving voltage.

The electron transport layer may further include at least one selectedfrom BCP, Bphen, Alq₃, BAlq, TAZ, and NTAZ:

In one or more embodiments, the electron transport layer may include atleast one of Compounds ET1 to ET25, but embodiments of the presentdisclosure are not limited thereto:

A thickness of the electron transport layer may be in a range of about100 Å to about 1,000 Å, for example, about 150 Å to about 500 Å. Whilenot wishing to be bound by theory, it is understood that when thethickness of the electron transport layer is within the range describedabove, the electron transport layer may have satisfactory electrontransport characteristics without a substantial increase in drivingvoltage.

Also, the electron transport layer may further include, in addition tothe materials described above, a metal-containing material.

The metal-containing material may include a Li complex. The Li complexmay include, for example, Compound ET-D1 (lithium 8-hydroxyquinolate,LiQ) or Compound ET-D2:

The electron transport region may include an electron injection layerthat promotes flow of electrons from the second electrode 19 thereinto.

The electron injection layer may include at least one selected from LiF,NaCl, CsF, Li₂, and BaO.

A thickness of the electron injection layer may be in a range of about 1Å to about 100 Å, for example, about 3 Å to about 90 Å. While notwishing to be bound by theory, it is understood that when the thicknessof the electron injection layer is within the range described above, theelectron injection layer may have satisfactory electron injectioncharacteristics without a substantial increase in driving voltage.

The second electrode 19 is disposed on the organic layer 15. The secondelectrode 19 may be a cathode. A material for forming the secondelectrode 19 may be selected from metal, an alloy, an electricallyconductive compound, and a combination thereof, which have a relativelylow work function. For example, lithium (Li), magnesium (Mg), aluminum(Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In),or magnesium-silver (Mg—Ag) may be used as a material for forming thesecond electrode 19. In one or more embodiments, to manufacture atop-emission type light-emitting device, a transmissive electrode formedusing ITO or IZO may be used as the second electrode 19.

Hereinbefore, the organic light-emitting device has been described withreference to the FIGURE, but embodiments of the present disclosure arenot limited thereto.

Another aspect of the present disclosure provides a diagnosticcomposition including at least one organometallic compound representedby Formula 1A.

The organometallic compound represented by Formula 1A provides highluminescent efficiency. Accordingly, a diagnostic composition includingthe organometallic compound may have high diagnostic efficiency.

The diagnostic composition may be used in various applications includinga diagnosis kit, a diagnosis reagent, a biosensor, and a biomarker.

The term “C₁-C₆₀ alkyl group” as used herein refers to a linear orbranched saturated aliphatic hydrocarbon monovalent group having 1 to 60carbon atoms, and non-limiting examples thereof include a methyl group,an ethyl group, a propyl group, an isobutyl group, a sec-butyl group, atert-butyl group, a pentyl group, an iso-amyl group, and a hexyl group.The term “C₁-C₆₀ alkylene group” as used herein refers to a divalentgroup having the same structure as the C₁-C₆₀ alkyl group.

The term “C₁-C₆₀ alkoxy group” as used herein refers to a monovalentgroup represented by —OA₁₀₁ (wherein A₁₀₁ is the C₁-C₆₀ alkyl group),and non-limiting examples thereof include a methoxy group, an ethoxygroup, and an iso-propyloxy (iso-propoxy) group.

The term “C₂-C₆₀ alkenyl group” as used herein refers to a hydrocarbongroup formed by including at least one carbon-carbon double bond in themiddle or at the terminus of the C₂-C₆₀ alkyl group, and examplesthereof include an ethenyl group, a propenyl group, and a butenyl group.The term “C₂-C₆₀ alkenylene group” as used herein refers to a divalentgroup having the same structure as the C₂-C₆₀ alkenyl group.

The term “C₂-C₆₀ alkynyl group” as used herein refers to a hydrocarbongroup formed by including at least one carbon-carbon triple bond in themiddle or at the terminus of the C₂-C₆₀ alkyl group, and examplesthereof include an ethynyl group, and a propynyl group. The term “C₂-C₆₀alkynylene group” as used herein refers to a divalent group having thesame structure as the C₂-C₆₀ alkynyl group.

The term “C₃-C₁₀ cycloalkyl group” as used herein refers to a monovalentsaturated hydrocarbon monocyclic group having 3 to 10 carbon atoms, andnon-limiting examples thereof include a cyclopropyl group, a cyclobutylgroup, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group.The term “C₃-C₁₀ cycloalkylene group” as used herein refers to adivalent group having the same structure as the C₃-C₁₀ cycloalkyl group.

The term “C₁-C₁₀ heterocycloalkyl group” as used herein refers to amonovalent saturated monocyclic group having at least one heteroatomselected from N, O, P, Si and S as a ring-forming atom and 1 to 10carbon atoms, and non-limiting examples thereof include atetrahydrofuranyl group, and a tetrahydrothiophenyl group. The term“C₁-C₁₀ heterocycloalkylene group” as used herein refers to a divalentgroup having the same structure as the C₁-C₁₀ heterocycloalkyl group.

The term “C₃-C₁₀ cycloalkenyl group” as used herein refers to amonovalent monocyclic group that has 3 to 10 carbon atoms and at leastone carbon-carbon double bond in the ring thereof, that is non-aromatic,and non-limiting examples thereof include a cyclopentenyl group, acyclohexenyl group, and a cycloheptenyl group. The term “C₃-C₁₀cycloalkenylene group” as used herein refers to a divalent group havingthe same structure as the C₃-C₁₀ cycloalkenyl group.

The term “C₁-C₁₀ heterocycloalkenyl group” as used herein refers to amonovalent monocyclic group that has at least one heteroatom selectedfrom N, O, P, Si, and S as a ring-forming atom, 1 to 10 carbon atoms,and at least one carbon-carbon double bond in its ring. Examples of theC₁-C₁₀ heterocycloalkenyl group are a 2,3-dihydrofuranyl group, and a2,3-dihydrothiophenyl group. The term “C₁-C₁₀ heterocycloalkenylenegroup” as used herein refers to a divalent group having the samestructure as the C₁-C₁₀ heterocycloalkenyl group.

The term “C₆-C₆₀ aryl group” as used herein refers to a monovalent grouphaving a carbocyclic aromatic system having 6 to 60 carbon atoms, andthe term “C₆-C₆₀ arylene group” as used herein refers to a divalentgroup having a carbocyclic aromatic system having 6 to 60 carbon atoms.Non-limiting examples of the C₆-C₆₀ aryl group include a phenyl group, anaphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenylgroup, and a chrysenyl group. When the C₆-C₆₀ aryl group and the C₆-C₆₀arylene group each include two or more rings, the rings may be fused toeach other.

The term “C₁-C₆₀ heteroaryl group” as used herein refers to a monovalentgroup having an aromatic system that has at least one heteroatomselected from N, O, P, Si, and S as a ring-forming atom, and 1 to 60carbon atoms. The term “C₁-C₆₀ heteroarylene group” as used hereinrefers to a divalent group having an aromatic system that has at leastone heteroatom selected from N, O, P, Si, and S as a ring-forming atom,and 1 to 60 carbon atoms. Non-limiting examples of the C₁-C₆₀ heteroarylgroup include a pyridinyl group, a pyrimidinyl group, a pyrazinyl group,a pyridazinyl group, a triazinyl group, a quinolinyl group, and anisoquinolinyl group. When the C₁-C₆₀ heteroaryl group and the C₁-C₆₀heteroarylene group each include two or more rings, the rings may befused to each other.

The term “C₆-C₆₀ aryloxy group” as used herein indicates —OA₁₀₂ (whereinA₁₀₂ is the C₆-C₆₀ aryl group), the term “C₆-C₆₀ arylthio group” as usedherein indicates —SA₁₀₃ (wherein A₁₀₃ is the C₆-C₆₀ aryl group), and theterm “C₇-C₆₀ arylalkyl group” as used herein indicates -A₁₀₄A₁₀₅(wherein A₁₀₄ is the C₆-C₅₉ aryl group and A₁₀₅ is the C₁-C₅₃ alkylgroup).

The term “monovalent non-aromatic condensed polycyclic group” as usedherein refers to a monovalent group (for example, having 8 to 60 carbonatoms) having two or more rings condensed to each other, only carbonatoms as ring-forming atoms, and no aromaticity in its entire molecularstructure. Examples of the monovalent non-aromatic condensed polycyclicgroup include a fluorenyl group. The term “divalent non-aromaticcondensed polycyclic group,” as used herein, refers to a divalent grouphaving the same structure as the monovalent non-aromatic condensedpolycyclic group.

The term “monovalent non-aromatic condensed heteropolycyclic group” asused herein refers to a monovalent group (for example, having 2 to 60carbon atoms) having two or more rings condensed to each other, aheteroatom selected from N, O, P, Si, and S, other than carbon atoms, asa ring-forming atom, and no aromaticity in its entire molecularstructure. Non-limiting examples of the monovalent non-aromaticcondensed heteropolycyclic group include a carbazolyl group. The term“divalent non-aromatic condensed heteropolycyclic group” as used hereinrefers to a divalent group having the same structure as the monovalentnon-aromatic condensed heteropolycyclic group.

The term “C₅-C₃₀ carbocyclic group” as used herein refers to a saturatedor unsaturated cyclic group having, as a ring-forming atom, 5 to 30carbon atoms only. The C₅-C₃₀ carbocyclic group may be a monocyclicgroup or a polycyclic group.

The term “C₁-C₃₀ heterocyclic group” as used herein refers to asaturated or unsaturated cyclic group having, as a ring-forming atom, atleast one heteroatom selected from N, O, Si, P, and S other than 1 to 30carbon atoms. The C₁-C₃₀ heterocyclic group may be a monocyclic group ora polycyclic group.

At least one substituent of the substituted C₅-C₃₀ carbocyclic group,the substituted C₂-C₃₀ heterocyclic group, the substituted C₁-C₆₀ alkylgroup, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substitutedC₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group,the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, thesubstituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group,the substituted C₇-C₆₀ arylalkyl group, the substituted C₁-C₆₀heteroaryl group, the substituted C₂-C₆₀ heteroaryloxy group, thesubstituted C₂-C₆₀ heteroarylthio group, the substituted C₃-C₆₀heteroarylalkyl group, the substituted monovalent non-aromatic condensedpolycyclic group, and the substituted monovalent non-aromatic condensedheteropolycyclic group may be selected from:

deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, aC₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group;

a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group,and a C₁-C₆₀ alkoxy group, each substituted with at least one selectedfrom deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H,—CFH₂, a hydroxyl group, a cyano group, a nitro group, an amino group,an amidino group, a hydrazine group, a hydrazone group, a carboxylicacid group or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, aC₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroarylgroup, a C₂-C₆₀ heteroaryloxy group, a C₂-C₆₀ heteroarylthio group, aC₃-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensedpolycyclic group, a monovalent non-aromatic condensed heteropolycyclicgroup, —N(Q₁₁)(Q₁₂), —S(Q₁₃)(Q₁₄)(Q₁₅), —B(Q₁₆)(Q₁₇), and—P(═O)(Q₁₈)(Q₁₉);

a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ heteroaryloxygroup, a C₂-C₆₀ heteroarylthio group, a C₃-C₆₀ heteroarylalkyl group, amonovalent non-aromatic condensed polycyclic group, and a monovalentnon-aromatic condensed heteropolycyclic group;

a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ heteroaryloxygroup, a C₂-C₆₀ heteroarylthio group, a C₃-C₆₀ heteroarylalkyl group, amonovalent non-aromatic condensed polycyclic group, and a monovalentnon-aromatic condensed heteropolycyclic group, each substituted with atleast one selected from deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂,—CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, anamino group, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkylgroup, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxygroup, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, aC₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ heteroaryloxygroup, a C₂-C₆₀ heteroarylthio group, a C₃-C₆₀ heteroarylalkyl group, amonovalent non-aromatic condensed polycyclic group, a monovalentnon-aromatic condensed heteropolycyclic group, —N(Q₂₁)(Q₂₂),—Si(Q₂₃)(Q₂₄)(Q₂₅), —B(Q₂₆)(Q₂₇), and —P(═O)(Q₂₈)(Q₂₉); and

—N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and —P(═O)(Q₃₈)(Q₃₉),and

Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ may each independentlybe selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxylgroup, a cyano group, a nitro group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₆₀ alkyl group, a C₁-C₆₀ alkyl group substituted with atleast one selected from deuterium, a C₁-C₆₀ alkyl group, and a C₆-C₆₀aryl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkylgroup, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, aC₆-C₆₀ aryl group, a C₆-C₆₀ aryl group substituted with at least oneselected from deuterium, a C₁-C₆₀ alkyl group, and a C₆-C₆₀ aryl group,a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkylgroup, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ heteroaryloxy group, a C₂-C₆₀heteroarylthio group, a C₃-C₆₀ heteroarylalkyl group, a monovalentnon-aromatic condensed polycyclic group, and a monovalent non-aromaticcondensed heteropolycyclic group.

When a group containing a specified number of carbon atoms issubstituted with any of the groups listed in the preceding paragraph,the number of carbon atoms in the resulting “substituted” group isdefined as the sum of the carbon atoms contained in the original(unsubstituted) group and the carbon atoms (if any) contained in thesubstituent. For example, when the term “substituted C₁-C₃₀ alkyl”refers to a C₁-C₃₀ alkyl group substituted with C₆-C₃₀ aryl group, thetotal number of carbon atoms in the resulting aryl substituted alkylgroup is C₇-C₆₀.

Hereinafter, a compound and an organic light-emitting device accordingto embodiments are described in detail with reference to SynthesisExamples and Examples. However, the organic light-emitting device is notlimited thereto. The wording “B was used instead of A” used indescribing Synthesis Examples means that the number of molar equivalentsof A used was identical to the number of molar equivalents of B used.

EXAMPLES Synthesis Example 1: Synthesis of Compound 1-1

Synthesis of Intermediate A(2-(5-bromo-3′,5′-di-tert-butyl-[1,1′-biphenyl]-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane)

10 grams (g) (0.024 moles, mol) of3,5-dibromo-3′,5′-di-tert-butyl-1,1′-biphenyl and 9.0 g (0.036 mol, 1.5equivalents, equiv.) of bispinacolato diboron were added to a flask, and4.6 g (0.048 mol, 2 equiv.) of potassium acetate and 0.96 g (0.05equiv.) of PdCl₂(dppf) were added to the flask. Then, 100 milliliters(ml) of toluene was added thereto, and the resultant mixture wasrefluxed overnight at a temperature of 100° C. The refluxed mixture thusobtained was cooled to room temperature, and the precipitate wasfiltered therefrom. The filtrate was washed by using ethyl acetate(EA)/H₂O, and purified by column chromatography to obtain 5.6 g (yield:50%) of Intermediate A. The obtained product was confirmed by MassSpectrometry and HPLC analysis.

HRMS (MALDI) calcd for C₂₆H₃₆BBrO₂: m/z 470.1992, found: 470.1994.

Synthesis of Intermediate B(2-(5-bromo-3′,5′-di-tert-butyl-[1,1′-biphenyl]-3-yl)pyridine)

5.6 g (0.014 mol, 1.2 equiv.) of Intermediate A, 1.9 g (0.012 mol, 1equiv.) of 2-bromopyridine, 0.61 g (0.001 mol, 0.07 equiv.) oftetrakis(triphenylphosphine)palladium(0), and 3.1 g (0.036 mol, 3equiv.) of potassium carbonate were dissolved in a solvent (25 mL, 0.8molar, M) in which tetrahydrofuran (THF) and distilled water (H₂O) weremixed at a ratio of 3:1, and the mixed solution was refluxed for 12hours. The refluxed mixture thus obtained was cooled to roomtemperature, and the precipitate was filtered therefrom. The filtratewas washed by using EA/H₂O, and purified by column chromatography (whileincreasing a volume rate of methylene chloride (MC)/hexane (Hex) tobetween 25% and 50%) to obtain 4 g (yield: 80%) of Intermediate B. Theobtained product was confirmed by Mass Spectrometry and HPLC analysis.

HRMS (MALDI) calcd for C₂₅H₂₈BrN: m/z 421.1405, found: 421.1407.

Synthesis of Intermediate C(2-(3′,5′-di-tert-butyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-[1,1′-biphenyl]-3-yl)pyridine)

4 g (0.009 mol) of Intermediate B(2-(5-bromo-3′,5′-di-tert-butyl-[1,1′-biphenyl]-3-yl)pyridine) and 3.6 g(0.014 mol, 1.5 equiv.) of bispinacolato diboron were added to a flask,and 1.9 g (0.019 mol, 2 equiv.) of potassium acetate and 0.39 g (0.05equiv.) of PdCl₂(dppf) were added to the flask. Then, 32 mL of toluenewas added thereto, and the resultant mixture was refluxed overnight at atemperature of 100° C. The refluxed mixture thus obtained was cooled toroom temperature, and the precipitate was filtered therefrom. Thefiltrate was washed by using EA/H₂O, and purified by columnchromatography to obtain 2.4 g (yield: 56%) of Intermediate C. Theobtained product was confirmed by Mass Spectrometry and HPLC analysis.

HRMS (MALDI) calcd for C₃₁H₄₀BNO₂: m/z 469.3152, found: 469.3155.

Synthesis of Intermediate E(2-(4-(3′,5′-di-tert-butyl-5-(pyridin-2-yl)-[1,1′-biphenyl]-3-yl)-1-methyl-1H-benzo[d]imidazol-2-yl)phenol)

2.4 g (0.005 mol, 1.2 equiv.) of Intermediate C, 1.3 g (0.004 mol, 1equiv.) of Intermediate D(2-(4-bromo-1-methyl-1H-benzo[d]imidazol-2-yl)phenol), 0.35 g (0.001mol, 0.07 equiv.) of tetrakis(triphenylphosphine)palladium(0), and 1.8 g(0.013 mol, 3 equiv.) of potassium carbonate were dissolved in 20 mL ofa solvent in which tetrahydrofuran (THF) and distilled water (H₂O) weremixed at a ratio of 3:1, and the mixed solution was refluxed for 12hours. The refluxed mixture thus obtained was cooled to roomtemperature, and the precipitate was filtered therefrom. The filtratewas washed by using EA/H₂O, and purified by column chromatography (whileincreasing a volume rate of MC/Hex to between 25% and 50%) to obtain 1.7g (yield: 73%) of Intermediate E. The obtained product was confirmed byMass Spectrometry and HPLC analysis.

HRMS (MALDI) calcd for C₃₉H₃₉N₃O: m/z 565.3093, found: 565.3096.

Synthesis of Compound 1-1

1.4 g (2.5 mmol) of Intermediate E and 1.23 g (3 mmol, 1.2 equiv.) ofK₂PtCl₄ were dissolved in 25 mL of a solvent in which 20 mL of AcOH and5 mL of H₂O were mixed, and the mixed solution was refluxed for 16hours. The refluxed mixture thus obtained was cooled to roomtemperature, and the precipitate was filtered therefrom. The precipitatewas dissolved again in MC and washed by using H₂O. The organic layer waspurified by column chromatography (MC 40%, EA 1%, Hex 59%) to obtain 0.7g (purity: 99% or more) of Compound 1-1. The obtained product wasconfirmed by Mass Spectrometry and HPLC analysis.

HRMS (MALDI) calcd for C₃₉H₃₇N₃OPt: m/z 758.26, found: 758.26.

Synthesis Example 2: Synthesis of Compound 1-28

Synthesis of Intermediate H

Intermediate H was synthesized in the same manner as Intermediate E inSynthesis Example 1, except that Intermediate F and Intermediate G wereused instead of Intermediate D and Intermediate C, respectively.

HRMS (MALDI) calcd for C₄₂H₄₇N₃OSi: m/z 637.3488, found: 637.3485.

Synthesis of Compound 1-28

Compound 1-28 (1.5 g, yield: 52%) was synthesized in the same manner asCompound 1-1 in Synthesis Example 1, except that Intermediate H was usedinstead of Intermediate E.

HRMS (MALDI) calcd for C₄₂H₄₅N₃OPtSi: m/z 830.2980, found: 830.2983.

Synthesis Example 3: Synthesis of Compound 1-30

Synthesis of Intermediate J

Intermediate J was synthesized in the same manner as Intermediate E inSynthesis Example 1, except that Intermediate F and Intermediate I wereused instead of Intermediate D and Intermediate C, respectively.

HRMS (MALDI) calcd for C₄₀H₄₁N₃O: m/z 579.3250, found: 579.3252.

Synthesis of Compound 1-30

Compound 1-30 (1.2 g, yield: 56%) was synthesized in the same manner asCompound 1-1 in Synthesis Example 1, except that Intermediate J was usedinstead of Intermediate E.

HRMS (MALDI) calcd for C₄₀H₃N₃OPt: m/z 772.2741, found: 772.2745.

Synthesis Example 4: Synthesis of Compound 1-17

Synthesis of Intermediate L

Intermediate L was synthesized in the same manner as Intermediate E inSynthesis Example 1, except that Intermediate F and Intermediate K wereused instead of Intermediate D and Intermediate C, respectively.

HRMS (MALDI) calcd for C₄₆H₄₅N₃₀: m/z 655.3563, found: 655.3567.

Synthesis of Compound 1-17

Compound 1-17 (1.7 g, yield: 57%) was synthesized in the same manner asCompound 1-1 in Synthesis Example 1, except that Intermediate L was usedinstead of Intermediate E.

HRMS (MALDI) calcd for C₄₆H₄₃N₃OPt: m/z 848.3054, found: 848.3053.

Synthesis Example 5: Synthesis of Compound 1-9

Synthesis of Intermediate N

Intermediate N was synthesized in the same manner as Intermediate E inSynthesis Example 1, except that Intermediate F and Intermediate M wereused instead of Intermediate D and Intermediate C, respectively.

HRMS (MALDI) calcd C₄₈H₅N₃OSi: m/z 713.3801, found: 713.3804.

Synthesis of Compound 1-9

Compound 1-9 (1.2 g, yield: 52%) was synthesized in the same manner asCompound 1-1 in Synthesis Example 1, except that Intermediate N was usedinstead of Intermediate E.

HRMS (MALDI) calcd for C₄₈H₄N₃OPtSi: m/z 906.3293, found: 906.3297.

Synthesis Example 6: Synthesis of Compound 1-12

Synthesis of Intermediate R

Intermediate R was synthesized in the same manner as Intermediate E inSynthesis Example 1, except that Intermediate F and Intermediate Q wereused instead of Intermediate D and Intermediate C, respectively.

HRMS (MALDI) calcd for C₄₅H₄₃N₃₀: m/z 641.3406, found: 641.3408.

Synthesis of Compound 1-12

Compound 1-12 (1.0 g, yield: 45%) was synthesized in the same manner asCompound 1-1 in Synthesis Example 1, except that Intermediate R was usedinstead of Intermediate E.

HRMS (MALDI) calcd for C₄₅H₄₁N₃OPt: m/z 834.2897, found: 834.2892.

Synthesis Example 7: Synthesis of Compound 3-417

Synthesis of Intermediate U

Intermediate U was synthesized in the same manner as Intermediate E inSynthesis Example 1, except that Intermediate S and Intermediate T wereused instead of Intermediate D and Intermediate C, respectively.

HRMS (MALDI) calcd for C₅₁H₄₉N₃₀: m/z 719.3876, found: 719.3874.

Synthesis of Compound 3-417

Compound 3-417 (1.2 g, yield: 55%) was synthesized in the same manner asCompound 1-1 in Synthesis Example 1, except that Intermediate U was usedinstead of Intermediate E.

HRMS (MALDI) calcd for C₄₅H₄₁N₃OPt: m/z 912.3367, found: 912.3369.

Example 1

An ITO glass substrate on which an ITO electrode (anode) is depositedwas cut to a size of 50 mm×50 mm×0.5 mm (mm=millimeter), sonicated withacetone, iso-propyl alcohol, and pure water each for 15 minutes, andcleaned by exposure to ultraviolet (UV) rays and ozone for 30 minutes.

Then, m-MTDATA was deposited on an ITO electrode (anode) of the glasssubstrate at a deposition rate of 1 Angstroms per second (A/sec) to forma hole injection layer having a thickness of 600 Angstroms (Å), andα-NPD (also referred to as NPB) was deposited on the hole injectionlayer at a deposition rate of 1 Å/sec to form a hole transport layerhaving a thickness of 250 Å.

Compound 1-28 (dopant) and CBP (host) were co-deposited on the holetransport layer at a deposition rate of 0.1 Å/sec and 1 Å/sec,respectively, to form an emission layer having a thickness of 400 Å.

BAlq was deposited on the emission layer at a deposition rate of 1 Å/secto form a hole blocking layer having a thickness of 50 Å, Alq₃ wasdeposited on the hole blocking layer to form an electron transport layerhaving a thickness of 300 Å, LiF was deposited on the electron transportlayer to form an electron injection layer having a thickness of 10 Å,and Al was vacuum-deposited on the electron injection layer to form asecond electrode (cathode) having a thickness of 1,200 Å, therebycompleting the manufacture of an organic light-emitting device having astructure of ITO/m-MTDATA (600 Å)/α-NPD (250 Å)/CBP+Compound 1-28 (10 wt%) (400 Å)/BAlq (50 Å)/Alq₃ (300 Å)/LiF (10 Å)/Al (1,200 Å).

Examples 2 to 6 and Comparative Examples 1 to 4

Organic light-emitting devices were manufactured in the same manner asin Example 1, except that Compounds shown in Table 2 were each usedinstead of Compound 1-28 as a dopant in forming an emission layer.

Evaluation Example 1: Evaluation of Characteristics of OrganicLight-Emitting Devices

The driving voltage, luminescent efficiency, quantum emissionefficiency, roll-off ratio, and lifespan (T₉₅) characteristics of theorganic light-emitting device manufactured according to Examples 1 to 6and Comparative Examples 1 to 4 were evaluated, and results thereof areshown in Table 2. Devices used for the evaluation were a current-voltagemeter (Keithley 2400) and a luminance meter (Minolta Cs-1000A). Thelifespan (T₉₅) (at 6,000 nit) indicates an amount of time that lapsedwhen luminance was 95% of initial luminance (100%) in a relative mannerwith respect to those of the organic light-emitting device of Example 6.The roll-off ratio was calculated according to Equation 20. Theluminescence efficiency are also provided in a relative manner withrespect to those of the organic light-emitting device of Example 5.Roll off={1−(efficiency at 9,000 nit/maximum light-emissionefficiency)}×100%  Equation 20

TABLE 2 Driving Luminescent Quantum Roll-off Lifespan (%) voltageefficiency (%) emission ratio (T₉₅) Dopant (V) (relative value)efficiency (%) (%) (relative value) Example 1 Compound 1-28 4.11 81% 84%14% 24% Example 2 Compound 1-30 4.14 80% 89% 15% 11% Example 3 Compound1-17 4.10 84% 87% 11% 28% Example 4 Compound 1-9  3.90 91% 91%  9% 15%Example 5 Compound 1-12 3.82 100%  100%   6% 75% Example 6  Compound3-417 3.94 92% 94% 10% 100%  Comparative Compound A 4.57 50% 69% 11% 18%Example 1 Comparative Compound B 4.00 61% 56%  9%  0% Example 2Comparative Compound C 4.97 62% 61% 35%  4% Example 3 ComparativeCompound D 4.78 57% 60% 19%  0% Example 4

Referring to Table 2, it was confirmed that the organic light-emittingdevices of Examples 1 to 6 have improved driving voltage, luminescentefficiency, quantum emission efficiency, roll-off ratio, and lifespancharacteristics, as compared with those of the organic light-emittingdevices of Comparative Examples 1 to 4.

As described above, an organometallic compound according to embodimentsof the present disclosure has excellent electrical characteristics andthermal stability, and accordingly, an organic light-emitting deviceincluding the organometallic compound may have excellent drivingvoltage, light-emission efficiency, quantum emission efficiency,roll-off ratio, and lifespan characteristics. In addition, due toexcellent phosphorescent luminescence characteristics of theorganometallic compound, the organometallic compound may provide adiagnostic composition having high diagnostic efficiency.

It should be understood that embodiments described herein should beconsidered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

While one or more embodiments have been described with reference to thefigures, it will be understood by those of ordinary skill in the artthat various changes in form and details may be made therein withoutdeparting from the spirit and scope of the present disclosure as definedby the following claims.

What is claimed is:
 1. An organometallic compound represented by Formula1A:

wherein, in Formula 1A, M is beryllium (Be), magnesium (Mg), aluminum(Al), calcium (Ca), titanium (Ti), manganese (Mn), cobalt (Co), copper(Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), ruthenium(Ru), rhodium (Rh), palladium (Pd), silver (Ag), rhenium (Re), platinum(Pt), or gold (Au), X₁ is O or S, and a bond between X₁ and M is acovalent bond, X₂ and X₃ are each independently C or N, X₄ is N, onebond selected from a bond between X₂ and M, a bond between X₃ and M, anda bond between X₄ and M is a covalent bond, and the others thereof areeach a coordinate bond, Y₁ and Y₃ to Y₅ are each independently C or N, abond between X₂ and Y₃, a bond between X₂ and Y₄, a bond between Y₄ andY₅, a bond between Y₅ and X₅₁, a bond between X₅₁ and Y₃ are each achemical bond, CY₁ to CY₅ are each independently selected from a C₅-C₃₀carbocyclic group and a C₁-C₃₀ heterocyclic group, wherein CY₃ is not anaphthalene group and CY₄ is not a benzimidazole group or anisoquinoline group, a cyclometallated ring formed by CY₅, CY₂, CY₃, andM is a 6-membered ring, X₅₁ is selected from O, S,N-[(L₇)_(b7)-(R₇)_(c7)], C(R₇)(R₈), Si(R₇)(R₈), Ge(R₇)(R₈), C(═O), N,C(R₇), Si(R₇), and Ge(R₇), R₇ and R₈ are optionally linked via a firstlinking group to form a substituted or unsubstituted C₅-C₃₀ carbocyclicgroup or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, L₁ toL₄ and L₇ are each independently selected from a substituted orunsubstituted C₅-C₃₀ carbocyclic group and a substituted orunsubstituted C₁-C₃₀ heterocyclic group, b1 to b4 and b7 are eachindependently an integer from 0 to 5, R₁ to R₄, R₇, and R₈ are eachindependently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅,a hydroxyl group, a cyano group, a nitro group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkylgroup, a substituted or unsubstituted C₂-C₆₀ alkenyl group, asubstituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted orunsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkylgroup, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, asubstituted or unsubstituted C₆-C₆₀ aryl group, a substituted orunsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstitutedC₆-C₆₀ arylthio group, a substituted or unsubstituted C₇-C₆₀ arylalkylgroup, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, asubstituted or unsubstituted C₂-C₆₀ heteroaryloxy group, a substitutedor unsubstituted C₂-C₆₀ heteroarylthio group, a substituted orunsubstituted C₃-C₆₀ heteroarylalkyl group, a substituted orunsubstituted monovalent non-aromatic condensed polycyclic group, asubstituted or unsubstituted monovalent non-aromatic condensedheteropolycyclic group, —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and—P(═O)(Q₈)(Q₉), c1 to c4 are each independently an integer from 1 to 5,c7 is 1, a1 to a4 are each independently 1, 2, 3, 4, or 5, two of aplurality of neighboring groups R₁ are optionally linked to form asubstituted or unsubstituted C₅-C₃₀ carbocyclic group or a substitutedor unsubstituted C₁-C₃₀ heterocyclic group, two of a plurality ofneighboring groups R₂ are optionally linked to form a substituted orunsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstitutedC₁-C₃₀ heterocyclic group, two of a plurality of neighboring groups R₃are optionally linked to form a substituted or unsubstituted C₅-C₃₀carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclicgroup, two of a plurality of neighboring groups R₄ are optionally linkedto form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or asubstituted or unsubstituted C₁-C₃₀ heterocyclic group, two or moreneighboring groups selected from R₁ to R₄ are optionally linked to forma substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substitutedor unsubstituted C₁-C₃₀ heterocyclic group, wherein i) at least oneselected from R₁ to R₄ is not hydrogen, ii) at least one selected fromR₁, R₂, and R₄ is not hydrogen, iii) at least one selected from R₁ to R₃is not hydrogen, or iv) at least one selected from R₁ and R₂ is nothydrogen, provided that, in cases where i) to viii) apply, at least oneselected from R₁ to R₄ is selected from a substituted or unsubstitutedC₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ arylgroup, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, asubstituted or unsubstituted monovalent non-aromatic condensedpolycyclic group, and a substituted or unsubstituted monovalentnon-aromatic condensed heteropolycyclic group, i) M is Pt, ii) X₁ is O,iii) X₂ and X₄ are each N, X₃ is C, a bond between X₂ and M and a bondbetween X₄ and M are each a coordinate bond, and a bond between X₃ and Mis a covalent bond, iv) Y₁ to Y₅ are each C, v) a bond between Y₅ andX₅₁ and a bond between Y₃ and X₅₁ are each a single bond, vi) CY₁, CY₂,and CY₃ are each a benzene group, and CY₄ is a pyridine group, vii) X₅₁is O, S, or N-[(L₇)_(b7)−(R₇)_(c7)], and viii) b7 is 0, c7 is 1, and R₇is a substituted or unsubstituted C₁-C₆₀ alkyl group, provided that wheni) M is Pt, ii) X₁ is O, iii) X₂ and X₄ are each N, X₃ is C, a bondbetween X₂ and M and a bond between X₄ and M are each a coordinate bond,and a bond between X₃ and M is a covalent bond, iv) Y₁ to Y₅ are each C,v) a bond between Y₅ and X₅₁ and a bond between Y₃ and X₅₁ are each asingle bond, vi) C₁, CY₂, and CY₃ are each a benzene group, and CY₄ is apyridine group, vii) X₅₁ is O, S, or NH, viii) a1, a2, and a4 are each0, and ix) a3 is 1, b3 is 0, and c3 is 1, then R₃ is not tert-butyl; atleast one substituent of the substituted C₅-C₃₀ carbocyclic group, thesubstituted C₁-C₃₀ heterocyclic group, the substituted C₁-C₆₀ alkylgroup, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substitutedC₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group,the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, thesubstituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group,the substituted C₇-C₆₀ arylalkyl group, the substituted C₁-C₆₀heteroaryl group, the substituted C₂-C₆₀ heteroaryloxy group, thesubstituted C₂-C₆₀ heteroarylthio group, the substituted C₃-C₆₀heteroarylalkyl group, the substituted monovalent non-aromatic condensedpolycyclic group, and the substituted monovalent non-aromatic condensedheteropolycyclic group is selected from: deuterium, —F, —C, —Br, —I,—CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group,a nitro group, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, C₁-C₆₀ alkyl group,a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxygroup; a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynylgroup, and a C₁-C₆₀ alkoxy group, each substituted with at least oneselected from deuterium, —F, —C, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃,—CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroarylgroup, a C₂-C₆₀ heteroaryloxy group, a C₂-C₆₀ heteroarylthio group, aC₃-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensedpolycyclic group, a monovalent non-aromatic condensed heteropolycyclicgroup, —N(Q₁₁)(Q₁₂), —S(Q₁₃)(Q₁₄)(Q₁₅), —B(Q₁₆)(Q₁₇), and—P(═O)(Q₁₈)(Q₁₉); a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkylgroup, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, aC₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, aC₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀heteroaryloxy group, a C₂-C₆₀ heteroarylthio group, a C₃-C₆₀heteroarylalkyl group, a monovalent non-aromatic condensed polycyclicgroup, and a monovalent non-aromatic condensed heteropolycyclic group; aC₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ heteroaryloxygroup, a C₂-C₆₀ heteroarylthio group, a C₃-C₆₀ heteroarylalkyl group, amonovalent non-aromatic condensed polycyclic group, and a monovalentnon-aromatic condensed heteropolycyclic group, each substituted with atleast one selected from deuterium, —F, —C, —Br, —I, —CD₃, —CD₂H, —CDH₂,—CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, C₁-C₆₀ alkyl group, a C₂-C₆₀alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenylgroup, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, aC₁-C₆₀ heteroaryl group, a C₂-C₆₀ heteroaryloxy group, a C₂-C₆₀heteroarylthio group, a C₃-C₆₀ heteroarylalkyl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅),—B(Q₂₆)(Q₂₇), and —P(═O)(Q₂₈)(Q₂₉); and —N(Q₃₁)(Q₃₂),—Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and —P(═O)(Q₃₈)(Q₃₉), and Q₁ to Q₉,Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ are each independently selectedfrom hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyanogroup, a nitro group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀alkyl group, a C₁-C₆₀ alkyl group substituted with at least one selectedfrom deuterium, a C₁-C₆₀ alkyl group, and a C₆-C₆₀ aryl group, a C₂-C₆₀alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenylgroup, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀aryl group substituted with at least one selected from deuterium, aC₁-C₆₀ alkyl group, and a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroarylgroup, a C₂-C₆₀ heteroaryloxy group, a C₂-C₆₀ heteroarylthio group, aC₃-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensedpolycyclic group, and a monovalent non-aromatic condensedheteropolycyclic group.
 2. The organometallic compound of claim 1,wherein CY₁ to CY₄ are each independently selected from a) a 6-memberedring, b) a condensed ring having two or more 6-membered rings that arecondensed to each other, and c) a condensed ring having two or more6-membered rings and one 5-membered ring that are condensed to eachother, wherein the 6-membererd ring is selected from a cyclohexanegroup, a cyclohexene group, an adamantane group, a norbornane group, anorbornene group, a benzene group, a pyridine group, a pyrimidine group,a pyrazine group, a pyridazine group, and a triazine group, and the5-membered ring is selected from a cyclopentane group, a cyclopentenegroup, a cyclopentadiene group, a furan group, a thiophene group, asilole group, a pyrrole group, a pyrazole group, an imidazole group, atriazole group, an oxazole group, an isoxazole group, a thiazole group,an isothiazole group, an oxadiazole group, and a thiadiazole group. 3.The organometallic compound of claim 1, wherein CY₁ to CY₄ are eachindependently selected from a benzene group, a naphthalene group, ananthracene group, a phenanthrene group, a triphenylene group, a pyrenegroup, a chrysene group, a cyclopentadiene group, a1,2,3,4-tetrahydronaphthalene group, a fluorene group, a carbazolegroup, a dibenzofuran group, a dibenzothiophene group, a dibenzosilolegroup, an azafluorene group, an azacarbazole group, an azadibenzofurangroup, an azadibenzothiophene group, an azadibenzosilole group, apyridine group, a pyrimidine group, a pyrazine group, a pyridazinegroup, a triazine group, a quinoline group, an isoquinoline group, aquinoxaline group, a quinazoline group, a phenanthroline group, acinnoline group, a phthalazine group, a 5,6,7,8-tetrahydroisoquinolinegroup, a 5,6,7,8-tetrahydroquinoline group, a5,6,7,8-tetrahydrophthalazine group, and a 5,6,7,8-tetrahydrocinnolinegroup.
 4. The organometallic compound of claim 1, wherein i) a bondbetween Y₃ and X₅₁ and a bond between Y₅ and X₅₁ are each a single bond,and X₅₁ is C(R₇)(R₈), Si(R₇)(R₈), or C(═O), ii) a bond between Y₃ andX₅₁ and a bond between Y₅ and X₅₁ are each a single bond, X₅₁ isN-[(L₇)_(b7)−(R₇)_(c7)], and R₇ is selected from a substituted orunsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstitutedC₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ arylgroup, a substituted or unsubstituted C₆-C₆₀ aryloxy group, asubstituted or unsubstituted C₆-C₆₀ arylthio group, a substituted orunsubstituted C₇-C₆₀ arylalkyl group, a substituted or unsubstitutedC₁-C₆₀ heteroaryl group, a substituted or unsubstituted C₂-C₆₀heteroaryloxy group, a substituted or unsubstituted C₂-C₆₀heteroarylthio group, a substituted or unsubstituted C₃-C₆₀heteroarylalkyl group, a substituted or unsubstituted monovalentnon-aromatic condensed polycyclic group, and a substituted orunsubstituted monovalent non-aromatic condensed heteropolycyclic group,or iii) one bond selected from a bond between Y₃ and X₅₁ and a bondbetween Y₅ and X₅₁ is a single bond while the other bond thereof is adouble bond, and X₅₁ is N, C(R₇), or Si(R₇).
 5. The organometalliccompound of claim 1, wherein X₅₁ is O, S, or N-[(L₇)_(b7)−(R₇)_(c7)], b7is 0, c7 is 1, R₇ is selected from: a C₁-C₃₀ alkyl group; and a C₁-C₃₀alkyl group substituted with at least one selected from deuterium, —F,—Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group,a cyano group, a nitro group, an amidino group, a hydrazine group, ahydrazone group, a carboxylic acid group or a salt thereof, a sulfonicacid group or a salt thereof, a phosphoric acid group or a salt thereof,C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, a norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinylgroup, a1 to a4 are each independently 1, 2, 3, or 4, at least oneselected from R₁ to R₄ are each independently selected from: acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl group, a norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenylgroup, an anthracenyl group, a fluoranthenyl group, a triphenylenylgroup, a pyrenyl group, a chrysenyl group, a pyrrolyl group, athiophenyl group, a furanyl group, an imidazolyl group, a pyrazolylgroup, a thiazolyl group, an isothiazolyl group, an oxazolyl group, anisoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinylgroup, a pyridazinyl group, an isoindolyl group, an indolyl group, anindazolyl group, a purinyl group, a quinolinyl group, an isoquinolinylgroup, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinylgroup, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group,a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group,an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolylgroup, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, atriazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, adibenzosilolyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, and an imidazopyrimidinyl group; and acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl group, a norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenylgroup, an anthracenyl group, a fluoranthenyl group, a triphenylenylgroup, a pyrenyl group, a chrysenyl group, a pyrrolyl group, athiophenyl group, a furanyl group, an imidazolyl group, a pyrazolylgroup, a thiazolyl group, an isothiazolyl group, an oxazolyl group, anisoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinylgroup, a pyridazinyl group, an isoindolyl group, an indolyl group, anindazolyl group, a purinyl group, a quinolinyl group, an isoquinolinylgroup, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinylgroup, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group,a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group,an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolylgroup, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, atriazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, adibenzosilolyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, and an imidazopyrimidinyl group, eachsubstituted with at least one selected from deuterium, —F, —Cl, —Br, —I,—CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group,a nitro group, an amino group, an amidino group, a hydrazine group, ahydrazone group, a carboxylic acid group or a salt thereof, a sulfonicacid group or a salt thereof, a phosphoric acid group or a salt thereof,a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, a norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenylgroup, an anthracenyl group, a fluoranthenyl group, a triphenylenylgroup, a pyrenyl group, a chrysenyl group, a pyrrolyl group, athiophenyl group, a furanyl group, an imidazolyl group, a pyrazolylgroup, a thiazolyl group, an isothiazolyl group, an oxazolyl group, anisoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinylgroup, a pyridazinyl group, an isoindolyl group, an indolyl group, anindazolyl group, a purinyl group, a quinolinyl group, an isoquinolinylgroup, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinylgroup, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group,a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group,an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolylgroup, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, atriazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, adibenzosilolyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, an imidazopyrimidinyl group, and—Si(Q₃₃)(Q₃₄)(Q₃₅), and Q₃₃ to Q₃₅ are each independently selected from:—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂; ann-propyl group, an iso-propyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and an n-propyl group, an iso-propyl group,an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butylgroup, an n-pentyl group, an isopentyl group, a sec-pentyl group, atert-pentyl group, a phenyl group, and a naphthyl group, eachsubstituted with at least one selected from deuterium, a C₁-C₁₀ alkylgroup, and a phenyl group.
 6. The organometallic compound of claim 1,wherein, in Formula 1A, a moiety represented by

is represented by one selected from Formulae CY1-1 to CY1-16:

wherein, in Formulae CY1-1 to CY1-16, Y₁ is the same as described inclaim 1, X₁₁ is N or C-[(L₁₁)_(b11)-(R₁₁)_(c11)], X₁₂ is N orC-[(L₁₂)_(b12)-(R₁₂)_(c12)], X₁₃ is N or C-[(L₁₃)_(b13)-(R₁₃)_(c13)],X₁₄ is N or C-[(L₁₄)_(b14)-(R₁₄)_(c14)], X₁₅ is N orC-[(L₁₅)_(b15)-(R₁₅)_(c15)], X₁₆ is N or C-[(L₁₆)_(b16)-(R₁₆)_(c16)],X₁₇ is N or C-[(L₁₇)_(b17)-(R₁₇)_(c17)], X₁₈ is N orC-[(L₁₈)_(b18)-(R₁₈)_(c18)], X₁₉ is C(R_(19a))(R_(19b)),N-[(L₁₉)_(b19)-(R₁₉)_(c19)], O, S, or Si(R_(19a))(R_(19b)), L₁₁ to L₁₉are each independently the same as described in connection with L₁ inclaim 1, b 11 to b19 are each independently the same as described inconnection with b 1 in claim 1, R₁₁ to R₁₉ and R_(19a) to R_(19c) areeach independently the same as described in connection with R₁ in claim1, c11 to c19 are each independently the same as described in connectionwith c1 in claim 1, *′ indicates a binding site to M of Formula 1A,and * indicates a binding site to CY₅ of Formula 1A.
 7. Theorganometallic compound of claim 1, wherein, in Formula 1A, a moietyrepresented by

is represented by one selected from Formulae CY2-1 to CY2-4:

wherein X₅₁ in Formula CY2-1 is O, S, N-[(L₇)_(b7)-(R₇)_(c7)],C(R₇)(R₈), Si(R₇)(R₈), Ge(R₇)(R₈), or C(═O), X₅₁ in Formulae CY2-2 toCY2-4 is N, C(R₇), Si(R₇), or Ge(R₇), L₇, b7, R₇, R₈, c7, and c8 areeach independently the same as described in claim 1, in Formulae CY2-1to CY2-4, X₂ is the same as described in claim 1, X₂₁ is N orC-[(L₂₁)_(b21)-(R₂₁)_(c21)], X₂₂ is N or C-[(L₂₂)_(b22)-(R₂₂)_(c22)],X₂₃ is N or C-[(L₂₃)_(b23)-(R₂₃)_(c23)], L₂₁ to L₂₃ are eachindependently the same as described in connection with L₂ in claim 1,b21 to b23 are each independently the same as described in connectionwith b2 in claim 1, R₂₁ to R₂₃ are each independently the same asdescribed in connection with R₂ in claim 1, c21 to c23 are eachindependently the same as described in connection with c2 in claim 1, *′indicates a binding site to M of Formula 1A, * indicates a binding siteto CY₁ of Formula 1A, and *″ indicates a binding site to CY₃ of Formula1A.
 8. The organometallic compound of claim 1, wherein, in Formula 1A, amoiety represented by

is represented by one selected from Formulae CY3-1 to CY3-11:

wherein, in Formulae CY3-1 to CY3-11, X₃ is the same as described inclaim 1, X₃₁ is N or C-[(L₃₁)_(b31)-(R₃₁)_(c31)], X₃₂ is N orC-[(L₃₂)_(b32)-(R₃₂)_(c32)], X₃₃ is N or C-[(L₃₃)_(b33)-(R₃₃)_(c33)],X₃₄ is N or C-[(L₃₄)_(b34)-(R₃₄)_(c34)], X₃₅ is N orC-[(L₃₅)_(b35)-(R₃₅)_(c35)], X₃₅ is N or C-[(L₃₆)_(b36)-(R₃₆)_(c36)],X₃₇ is N or C-[(L₃₇)_(b37)-(R₃₇)_(c37)], X₃₉ is C(R_(39a))(R_(39b)),N-[(L₃₉)_(b39)-(R₃₉)_(c39)], O, S, or Si(R_(39a))(R_(39b)), L₃₁ to L₃₇and L₃₉ are each independently the same as described in connection withL₃ in claim 1, b31 to b37 and b39 are each independently the same asdescribed in connection with b3 in claim 1, R₃₁ to R₃₉ and R_(39a) toR_(39b) are each independently the same as described in connection withR₃ in claim 1, c31 to c37 and c39 are each independently the same asdescribed in connection with c3 in claim 1, *′ indicates a binding siteto M of Formula 1A, * indicates a binding site to CY₄ of Formula 1A, and*″ indicates a binding site to CY₂ of Formula 1A.
 9. The organometalliccompound of claim 1, wherein, in Formula 1A, a moiety represented by

is represented by one selected from Formulae CY4-1 to CY4-16:

wherein, in Formulae CY4-1 to CY4-16, X₄ is the same as described inclaim 1, X₄₁ is N or C-[(L₄₂)_(b42)-(R₄₂)_(c42)], X₄₃ is N orC-[(L₄₃)_(b43)-(R₄₃)_(c43)], X₄₄ is N or C-[(L₄₄)_(b44)-(R₄₄)_(c44)],X₄₅ is N or C-[(L₄₅)_(b45)-(R₄₅)_(c45)], X₄₆ is N orC-[(L₄₆)_(b46)-(R₄₆)_(c46)], X₄₇ is N or C-[(L₄₇)_(b47)-(R₄₇)_(c47)],X₄₈ is N or C-[(L₄₈)_(b48)-(R₄₈)_(c48)], X₄₉ is C(R_(49a))(R_(49b)),N-[(L₄₉)_(b49)-(R₄₉)_(c49)], O, S, or Si(R_(49a))(R_(49b)), L₄₁ to L₄₉are each independently the same as described in connection with L₄ inclaim 1, b41 to b49 are each independently the same as described inconnection with b4 in claim 1, R₄₁ to R₄₉ and R_(49a) to R_(49c) areeach independently the same as described in connection with R₄ in claim1, c41 to c49 are each independently the same as described in connectionwith c4 in claim 1, *′ indicates a binding site to M of Formula 1A,and * indicates a binding site to CY₃ of Formula 1A.
 10. Theorganometallic compound of claim 1, wherein, in Formula 1A, a moietyrepresented by

is represented by one selected from Formulae CY1(1) to CY1(8), a moietyrepresented by

is represented by one selected from Formulae CY2(1) to CY2(4), a moietyrepresented by

is represented by one selected from Formulae CY3(1) to CY3(24), and amoiety represented by

is represented by one selected from Formulae CY4(1) to CY4(67):

wherein, X₅₁ in Formulae CY2(1) to CY2(4) is O, S,N-[(L₇)_(b7)−(R₇)_(c7)], C(R₇)(R₈), Si(R₇)(R₈), Ge(R₇)(R₈), or C(═O),and L₇, b7, R₇, R₈, c7, and c8 are each independently the same asdescribed in claim 1, in Formulae CY1(1) to CY1(8), CY2(1) to CY2(4),CY3(1) to CY3(24), and CY4(1) to CY4(67), X₂ to X₄, Y₁, L₁ to L₄, b1 tob4, R₁ to R₄, and c1 to c4 are each independently the same as describedin claim 1, X₃₉ is C(R_(39a))(R_(39b)), N-[(L₃₉)_(b39)-(R₃₉)_(c39)], O,S, or Si(R_(39a))(R_(39b)), X₄₉ is C(R_(49a))(R_(49a)),N-[(L₄₉)_(b49)-(R₄₉)_(c49)], O, S, or Si(R_(49a))(R_(49b)), L_(1a) andL_(1b) are each independently the same as described in connection withL₁ in claim 1, R_(1a) and R_(1b) are each independently the same asdescribed in connection with R₁ in claim 1, L_(3a), L_(3b), and L₃₉ areeach independently the same as described in connection with L₃ in claim1, R_(3a), R_(3b), R₃₉, R_(39a), and R_(39b) are each independently thesame as described in connection with R₃ in claim 1, b39 and c39 are eachindependently the same as described in connection with b3 and c3 inclaim 1, respectively, L_(4a), L_(4b), and L₄₉ are each independentlythe same as described in connection with L₄ in claim 1, R_(4a), R_(4b),R₄₉, R_(49a), and R_(49b) are each independently the same as describedin connection with R₄ in claim 1, b49 and c49 are each independently thesame as described in connection with b4 and c4 in claim 1, respectively,*—(L₁)_(b1)-(R₁)_(c1), *—(L_(1a))_(b1)-(R_(1a))_(c1),*—(L_(1b))_(b1)-(R_(1b))_(c1), *—(L₂)_(b2)-(R₂)_(c2), *—(L₃)_(b3)-(R₃)_(c3)], *—(L_(3a))_(b3)-(R_(3a))_(c3),*—(L_(3b))_(b3)-(R_(3b))_(c3), *—(L₄)_(b4)-(R₄)_(c4),*—(L_(4a))_(b4)-(R_(4a))_(c4), and *—(L_(4b))_(b4)-(R_(4b))_(c4) are nothydrogen, and * indicates a binding site to a neighboring atom, inFormulae CY1(1) to CY1(8), CY2(1) to CY2(4), CY3(1) to CY3(24), andCY4(1) to CY4(67), *′ indicates a binding site to M of Formula 1A, inFormulae CY1(1) to CY1(8), * indicates a binding site to CY₅ of Formula1A, in Formulae CY2(1) to CY2(4), * indicates a binding site to CY₁ ofFormula 1A, and *” indicates a binding site to CY₃ of Formula 1A, inFormulae CY3(1) to CY3(24), *” indicates a binding site to CY₂ ofFormula 1A, and * indicates a binding site to CY4 of Formula 1A, and inFormulae CY4(1) to CY4(67), * indicates a binding site to CY₃ of Formula1A.
 11. The organometallic compound of claim 1, wherein theorganometallic compound is represented by Formula 1-1:

wherein, in Formula 1-1, M, X₁ to X₃, and X₅₁ are each independently thesame as described in claim 1, X₁₁ is N or C-[(L₁₁)_(b11)-(R₁₁)_(c11)],X₁₂ is N or C-[(L₁₂)_(b12)-(R₁₂)_(c12)], X₁₃ is N orC-[(L₁₃)_(b13)-(R₁₃)_(c13)], X₁₄ is N or C-[(L₁₄)_(b14)-(R₁₄)_(c14)],L₁₁ to L₁₄, b11 to b14, R₁₁ to R₁₄ and c11 to c14 are each independentlythe same as described in connection with L₁, b1, R₁, and c1 in claim 1,respectively, X₂₁ is N or N or C-[(L₂₁)_(b21)-(R₂₁)_(c21)], X₂₂ is N orC-[(L₂₂)_(b22)-(R₂₂)_(c22)], X₂₃ is N or C-[(L₂₃)_(b23)-(R₂₃)_(c23)],L₂₁ to L₂₃, b21 to b23, R₂₁ to R₂₃ and c21 to c23 are each independentlythe same as described in connection with L₂, b2, R₂, and c2 in claim 1,respectively, X₃₁ is N or C-[(L₃₁)_(b31)-(R₃₁)_(c31)], X₃₂ is N orC-[(L₃₂)_(b32)-(R₃₂)_(c32)], X₃₃ is N or C-[(L₃₃)_(b33)-(R₃₃)_(c33)],L₃₁ to L₃₃, b31 to b33, R₃₁ to R₃₃ and c31 to c33 are each independentlythe same as described in connection with L₃, b3, R₃, and c3 in claim 1,X₄₁ is N or C-[(L₄₁)_(b41)-(R₄₁)_(c41)], X₄₂ is N orC-[(L₄₂)_(b42)-(R₄₂)_(c42)], X₄₃ is N or C-[(L₄₃)_(b43)-(R₄₃)_(c43)],X₄₄ is N or C-[(L₄₄)_(b44)-(R₄₄)_(c44)], L₄₁ to L₄₄, b41 to b44, R₄₁ toR₄₄ and c41 to c44 are each independently the same as described inconnection with L₄, b4, R₄, and c4 in claim 1, two selected from R₁₁ toR₁₄ are optionally linked to form a substituted or unsubstituted C₅-C₃₀carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclicgroup, two selected from R₂₁ to R₂₃ are optionally linked to form asubstituted or unsubstituted C₅-C₃₀ carbocyclic group or a substitutedor unsubstituted C₁-C₃₀ heterocyclic group, two selected from R₃₁ to R₃₃are optionally linked to form a substituted or unsubstituted C₅-C₃₀carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclicgroup, and two selected from R₄₁ to R₄₄ are optionally linked to form asubstituted or unsubstituted C₅-C₃₀ carbocyclic group or a substitutedor unsubstituted C₁-C₃₀ heterocyclic group.
 12. An organiclight-emitting device comprising: a first electrode; a second electrode;and an organic layer disposed between the first electrode and the secondelectrode, wherein the organic layer comprising an emission layer, andwherein the organic layer comprises at least one organometallic compoundof claim
 1. 13. The organic light-emitting device of claim 12, whereinthe first electrode is an anode, the second electrode is a cathode, theorganic layer further comprises a hole transport region disposed betweenthe first electrode and the emission layer and an electron transportregion disposed between the emission layer and the second electrode, thehole transport region comprises a hole injection layer, a hole transportlayer, an electron blocking layer, or any combination thereof, and theelectron transport region comprises a hole blocking layer, an electrontransport layer, an electron injection layer, or any combinationthereof.
 14. The organic light-emitting device of claim 12, wherein theemission layer comprises the organometallic compound.
 15. The organiclight-emitting device of claim 14, wherein the emission layer furthercomprises a host, and an amount of the host in the emission layer isgreater than an amount of the organometallic compound in the emissionlayer.
 16. An organometallic compound represented by Formula 1-1:

wherein, in Formula 1-1, M is platinum (Pt), X₁ is O, X₂ is N, X₃ is C,X₅₁ is N-[(L₇)_(b7)-(R₇)_(c7)], X₁₁ is C-[(L₁₁)_(b11)-(R₁₁)_(c11)], X₁₂is C-[(L₁₂)_(b12)-(R₁₂)_(c12)], X₁₃ is C-[(L₁₃)_(b13)-(R₁₃)_(c13)], X₁₄is C-[(L₁₄)_(b14)-(R₁₄)_(c14)], X₂₁ is is C-[(L₂₁)_(b21)-(R₂₁)_(c21)],X₂₂ is C-[(L₂₂)_(b22)-(R₂₂)_(c22)], X₂₃ is C-[(L₂₃)_(b23)-(R₂₃)_(c23)],X₃₁ is is C-[(L₃₁)_(b31)-(R₃₁)_(c31)], X₃₂ isC-[(L₃₂)_(b32)-(R₃₂)_(c32)], X₃₃ is C-[(L₃₃)_(b33)-(R₃₃)_(c33)], X₄₁ isis C-[(L₄₁)_(b41)-(R₄₁)_(c41)], X₄₂ is C-[(L₄₂)_(b42)-(R₄₂)_(c42)], X₄₃is C-[(L₄₃)_(b43)-(R₄₃)_(c43)], X₄₄ is C-[(L₄₄)_(b44)-(R₄₄)_(c44)], L₇,L₁₁ to L₁₄, L₂₁ to L₂₃, L₃₁ to L₃₃ and L₄₁ to L₄₄ are each independentlyselected from a substituted or unsubstituted C₅-C₃₀ carbocyclic groupand a substituted or unsubstituted C₁-C₃₀ heterocyclic group, b7, b11 tob14, b21 to b23, b31 to b33 and b41 to b44 are each independently aninteger from 0 to 5, R₇, R₁₁ to R₁₄, R₂₁ to R₂₃, R₃₁ to R₃₃ and R₄₁ toR₄₄ are each independently selected from hydrogen, deuterium, —F, —Cl,—Br, —I, —SF₅, a hydroxyl group, a cyano group, a nitro group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a substituted or unsubstitutedC₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group,a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted orunsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkylgroup, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, asubstituted or unsubstituted C₆-C₆₀ aryl group, a substituted orunsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstitutedC₆-C₆₀ arylthio group, a substituted or unsubstituted C₇-C₆₀ arylalkylgroup, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, asubstituted or unsubstituted C₂-C₆₀ heteroaryloxy group, a substitutedor unsubstituted C₂-C₆₀ heteroarylthio group, a substituted orunsubstituted C₃-C₆₀ heteroarylalkyl group, a substituted orunsubstituted monovalent non-aromatic condensed polycyclic group, asubstituted or unsubstituted monovalent non-aromatic condensedheteropolycyclic group, —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and—(═O)(Q₈)(Q₉), c11 to c14, c21 to c23, c31 to c33 and c41 to c44 areeach independently an integer from 1 to 5, c7 is 1, two selected fromR₁₁ to R₁₄ are optionally linked to form a substituted or unsubstitutedC₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀heterocyclic group, two selected from R₂₁ to R₂₃ are optionally linkedto form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or asubstituted or unsubstituted C₁-C₃₀ heterocyclic group, two selectedfrom R₃₁ to R₃₃ are optionally linked to form a substituted orunsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstitutedC₁-C₃₀ heterocyclic group, and two selected from R₄₁ to R₄₄ areoptionally linked to form a substituted or unsubstituted C₅-C₃₀carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclicgroup, provided that, when i) b7 is 0, and ii) R₇ is a substituted orunsubstituted C₁-C₆₀ alkyl group, then one of R₁₁ to R₁₄, one of R₂₁ toR₂₃, one of R₃₁ to R₃₃, one of R₄₁ to R₄₄, or any combination thereof isselected from a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, asubstituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted orunsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted orunsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₁-C₆₀heteroaryl group, a substituted or unsubstituted monovalent non-aromaticcondensed polycyclic group, and a substituted or unsubstitutedmonovalent non-aromatic condensed heteropolycyclic group, provided thatwhen i) X₅₁ is NH, ii) X₁₁ is CH, X12 is CH, X₁₃ is CH, X₁₄ is CH, X₂₁is CH, X₂₂ is CH, X₂₃ is CH, X₃₁ is CH, X₃₃ is CH, X₄₁ is CH, X₄₂ is CH,X₄₃ is CH, and X₄₄ is CH, and iii) b3 is 0, and c3 is 1, then R₃ is nottert-butyl; and at least one substituent of the substituted C₅-C₃₀carbocyclic group, the substituted C₁-C₃₀ heterocyclic group, thesubstituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group,the substituted C₂-C₆₀ alkynyl group, the substituted C₂-C₆₀ alkoxygroup, the substituted C₃-C₂₀ cycloalkyl group, the substituted C₂-C₂₀heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, thesubstituted C₁-C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ arylgroup, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀arylthio group, the substituted C₇-C₆₀ arylalkyl group, the substitutedC₁-C₆₀ heteroaryl group, the substituted C₂-C₆₀ heteroaryloxy group, thesubstituted C₂-C₆₀ heteroarylthio group, the substituted C₃-C₆₀heteroarylalkyl group, the substituted monovalent non-aromatic condensedpolycyclic group, and the substituted monovalent non-aromatic condensedheteropolycyclic group is selected from: deuterium, —F, —Cl, —Br, —I,—CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group,a nitro group, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, C₁-C₆₀ alkyl group,a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxygroup; a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynylgroup, and a C₁-C₆₀ alkoxy group, each substituted with at least oneselected from deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃,—CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroarylgroup, a C₂-C₆₀ heteroaryloxy group, a C₂-C₆₀ heteroarylthio group, aC₃-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensedpolycyclic group, a monovalent non-aromatic condensed heteropolycyclicgroup, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅), —B(Q₁₆)(Q₁₇), and—(═O)(Q₁₈)(Q₁₉); a C₃-C₁₀ ycloalkyl group, a C₁-C₁₀ heterocycloalkylgroup, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, aC₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, aC₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀heteroaryloxy group, a C₂-C₆₀ heteroarylthio group, a C₃-C₆₀heteroarylalkyl group, a monovalent non-aromatic condensed polycyclicgroup, and a monovalent non-aromatic condensed heteropolycyclic group; aC₃-C₆₀ cycloalkyl group, a C₁-C₆₀ heterocycloalkyl group, a C₃-C₆₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ heteroaryloxygroup, a C₂-C₆₀ heteroarylthio group, a C₃-C₆₀ heteroarylalkyl group, amonovalent non-aromatic condensed polycyclic group, and a monovalentnon-aromatic condensed heteropolycyclic group, each substituted with atleast one selected from deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂,—CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, C₁-C₆₀ alkyl group, a C₂-C₆₀alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenylgroup, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, aC₁-C₆₀ heteroaryl group, a C₂-C₆₀ heteroaryloxy group, a C₂-C₆₀heteroarylthio group, a C₃-C₆₀ heteroarylalkyl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅),—B(Q₂₆)(Q₂₇), and —(═O)(Q₂₈)(Q₂₉); and —N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅),—B(Q₃₆)(Q₃₇), and —(═O)(Q₃₈)(Q₃₉), and Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉,and Q₃₁ to Q₃₉ are each independently selected from hydrogen, deuterium,—F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₆₀alkyl group substituted with at least one selected from deuterium, aC₁-C₆₀ alkyl group, and a C₆-C₆₀ aryl group, a C₂-C₆₀ alkenyl group, aC₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group,a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryl groupsubstituted with at least one selected from deuterium, a C₁-C₆₀ alkylgroup, and a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, aC₂-C₆₀ heteroaryloxy group, a C₂-C₆₀ heteroarylthio group, a C₃-C₆₀heteroarylalkyl group, a monovalent non-aromatic condensed polycyclicgroup, and a monovalent non-aromatic condensed heteropolycyclic group.17. The organometallic compound of claim 16, wherein, in Formula 1-1, amoiety represented by

is represented by Formula CY2-1:

in Formula CY2-1, *′ indicates a binding site to M of Formula 1-1, *indicates a binding site to a neighboring atom of Formula 1-1, and *″indicates a binding site to a neighboring atom of Formula 1-1.
 18. Anorganic light-emitting device comprising: a first electrode; a secondelectrode; and an organic layer disposed between the first electrode andthe second electrode, wherein the organic layer comprising an emissionlayer, and wherein the organic layer comprises at least oneorganometallic compound of claim
 16. 19. The organic light-emittingdevice of claim 18, wherein the first electrode is an anode, the secondelectrode is a cathode, the organic layer further comprises a holetransport region disposed between the first electrode and the emissionlayer and an electron transport region disposed between the emissionlayer and the second electrode, the hole transport region comprises ahole injection layer, a hole transport layer, an electron blockinglayer, or any combination thereof, and the electron transport regioncomprises a hole blocking layer, an electron transport layer, anelectron injection layer, or any combination thereof.
 20. The organiclight-emitting device of claim 18, wherein the emission layer comprisesthe organometallic compound.
 21. The organic light-emitting device ofclaim 20, wherein the emission layer further comprises a host, and anamount of the host in the emission layer is greater than an amount ofthe organometallic compound in the emission layer.